Donor-Acceptor Aggregation-induced Emission Luminogen with Multi-stimuli Responsive Behavior

ABSTRACT

Provided herein are aggregation-induced emission luminogens, methods of preparation and use thereof, and devices and sensors comprising the same. The aggregation-induced emission luminogens can exhibit multi-stimuli responsive emissions.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority of U.S. ProvisionalApplication No. 62/920,554, filed on May 6, 2019, the contents of whichbeing hereby incorporated by reference in their entirety for allpurposes.

TECHNICAL FIELD

The present disclosure generally relates to aggregation-induced emissionluminogens (AIEgen) and methods of preperation and use thereof. Moreparticularly, the present disclosure relates to multi-stimuli responsiveAIEgens, methods of use and preparation thereof, and devices and sensorscomprising the same.

BACKGROUND

Organisms show various adaptive behaviors and a wide variety ofintriguing ways to respond to stimulus from their surroundingenvironment. For example, Mimosa pudica is very sensitive to externalstimuli and its leaves quickly close and petiole hangs down in responseto tactile stimulations, such as wind, vibration, touch and electricaland mechanical stimulation. Chameleons are well-known for theirremarkable ability to instantaneously shift the skin color in responseto the surrounding temperature and light stimulus. Such examples arenumerous. Today, scientists and engineers are fascinated by thesestimuli-responsive behaviors, because investigation of these behaviorsmay yield new inspiration for developing diverse bio-inspired and smartmaterials for real-world applications. One common principle learned fromthese natural creatures is that their unique and complex physiologicalfunctions are derived from their selective integration capability ofeach particular function related to different kinds of specializedcells. And this principle has been efficiently utilized for fabricationof various novel materials by researchers through assembling differentstructural components with special function into composite systems atthe molecular level to achieve multi-functional materials.

At present, there is still an urgent demand for novel smart materialsthat are able to support more efficient technologies and to achieve adiverse range of practical applications in synthetic material area. Byutilizing the same bio-inspired integration strategy, materialscientists have developed a wide variety of new smart systems that areable to response to multiple environmental stimuli. For instance,Thayumanavan et al. reported a novel triple stimuli sensitive blockcopolymer assembly with responses to changes in temperature, pH andredox potential by incorporating an acid-sensitivetetrahydropyran-protected 2-hydroxyethylmethacrylate (THP protectedHEMA) and a temperature-sensitive poly(N-isopropylacrylamide) (PNIPAM)with a redox sensitive disulfide linker. Weder's group reported thefirst supramolecular polymer materials with thermomechanicalcharacteristics of a supramolecular polymer glass by combiningmechanoresponsive luminescent compounds with the concept ofsupramolecular polymerization. Wang and co-workers prepared triplestimulus sensitive supramolecular hydrogel that responded to changes intemperature, light and reduction through the combination ofcyclodextrin-based host-guest complexes, poly(N-isopropylacrylamide)chains, azobenzene groups and disulfide bonds. Accordingly, thesemultiple responsive systems are generally constructed by the integrationof multiple components with specific responsive ability. Thus, precisecontrol of each component and time-consuming organic synthesis arerequired.

Owing to the vacant p-orbital on its central boron atom, triarylborons(TAB) serve as excellent electron acceptors. When conjugated toamine-based electron donor, the resulting donor-acceptor (D-A)small-molecule systems can show unprecedented photophysical andphotochemical properties resulting from intramolecular charge transfer(ICT), which have extensive applications in optical storage and memory,optoelectronic and display devices, chemical sensors, security inks andpapers, etc. have been developed. While a majority of reported TAB-aminesystems only exhibit one specific responsive function, little effort hadbeen placed to explore their versatility and capacity in multifariousapplications. In this respect, it would be desirable if multipleindividual responsive properties could be integrated into a single smallmolecule system in a similar way that organisms do without involvingtedious synthetic tasks. There is thus a need for simple and versatilesmall molecule materials with various kinds of environmental responses.

SUMMARY

Provided herein is a versatile TAB-containing compounds with a D-Astructure, aggregation-induced emission (AIE) and pronounced ICT effect.This luminogen is sensitive to multiple stimulus, including solvent,temperature, mechanical shearing force, hydrostatic pressure andelectric field. Each of them being specifically visualized by aprominent photoluminescence (PL) color change. The compound describedherein exhibit multiple responsive properties, including solvatochromicPL, thermochromic PL, mechanochromic PL, electrochromism andelectrochromic PL as well as electroluminescence, in a single smallmolecule system, which is rarely reported. Another unique aspect of thepresent system is that each responsive behavior has its own specialty.

In a first aspect, provided herein is a compound having the Formula 1:

wherein each of Ar¹, Ar², Ar³, Ar⁴, Ar⁵, Ar⁶, and Ar⁷ is independentlyselected from the group consisting of aryl and heteroaryl.

In a first embodiment, provided herein is the compound of the firstaspect, wherein the compound is represented by the Formula 2:

wherein each of m and n is independently 1, 2, 3, or 4;

R¹ and R² for each instance is independently selected from the groupconsisting of hydrogen, halide, nitrile, nitro, —OR, —SR, —NR₂, —(C═O)R,—(C═O)OR, —(C═O)NR₂, —N(R)(C═O)R, —O(C═O)R, —N(R)(C═O)OR, —O(C═O)NR₂,—SO₂R, —SO₂NR₂, alkyl, cycloalkyl, alkenyl, alkynyl, aryl,heterocycloalkyl, and heteroaryl; or two instance of R¹ taken togetherform a 5-6 membered cycloalkyl, heterocycloalkyl, aryl, or heteroaryl;or two instance of R² taken together form a 5-6 membered cycloalkyl,heterocycloalkyl, aryl, or heteroaryl; or one instance of R¹ and oneinstance of R² taken together form a covalent bond; and

R for each instance is independently selected from the group consistingof hydrogen, alkyl, cycloalkyl, alkenyl, alkynyl, aryl,heterocycloalkyl, and heteroaryl; or two instances of R taken togetherform a 3-6 membered heterocycloalkyl.

In a second embodiment, provided herein is the compound of the firstaspect, wherein the compound has the Formula 3:

wherein each of m and n is independently 1, 2, 3, or 4;

each of o, p, q, t, and u is independently 1, 2, 3, 4, or 5;

R¹ and R² for each instance is independently selected from the groupconsisting of hydrogen, halide, nitrile, nitro, —OR, —SR, —NR₂, —(C═O)R,—(C═O)OR, —(C═O)NR₂, —N(R)(C═O)R, —O(C═O)R, —N(R)(C═O)OR, —O(C═O)NR₂,—SO₂R, —SO₂NR₂, alkyl, cycloalkyl, alkenyl, alkynyl, aryl,heterocycloalkyl, and heteroaryl; or two instance of R¹ taken togetherform a 5-6 membered cycloalkyl, heterocycloalkyl, aryl, or heteroaryl;or two instance of R² taken together form a 5-6 membered cycloalkyl,heterocycloalkyl, aryl, or heteroaryl; or one instance of R¹ and oneinstance of R² taken together form a covalent bond;

R³, R⁴, R⁵, R⁶, and R⁷ for each instance is independently selected fromthe group consisting of hydrogen, halide, nitrile, nitro, —OR, —SR,—NR₂, —(C═O)R, —(C═O)OR, —(C═O)NR₂, —N(R)(C═O)R, —O(C═O)R, —N(R)(C═O)OR,—O(C═O)NR₂, —SO₂R, —SO₂NR₂, alkyl, cycloalkyl, alkenyl, alkynyl, aryl,heterocycloalkyl, and heteroaryl; or one instance of R⁴ and on instanceof R⁵ form a covalent bond; or one instance of R³ and one instance of R¹taken together form a covalent bond; or one instance of R³ and oneinstance of R⁴ taken together form a covalent bond; or one instance ofR¹ and one instance of R⁵ taken together form a covalent bond; or oneinstance of R² and one instance of R⁵ taken together form a covalentbond; or one instance of R² and one instance of R⁷ taken together form acovalent bond; or one instance of R⁶ and one instance of R⁷ takentogether form a covalent bond; and

R for each instance is independently selected from the group consistingof hydrogen, alkyl, cycloalkyl, alkenyl, alkynyl, aryl,heterocycloalkyl, and heteroaryl; or two instances of R taken togetherform a 3-6 membered heterocycloalkyl.

In a third embodiment, provided herein is the compound of the secondembodiment of the first aspect, wherein each of m and n is independently1 or 2; each of o, p, q, t, and u is independently 1, 2, or 3;

R¹ and R² for each instance is independently selected from the groupconsisting of hydrogen, halide, nitrile, nitro, —OR, —NR₂, alkyl,cycloalkyl, alkenyl, alkynyl, aryl, heterocycloalkyl, and heteroaryl;

R³, R⁴, R⁵, R⁶, and R⁷ for each instance is independently selected fromthe group consisting of hydrogen, halide, nitrile, nitro, —OR, —NR₂,alkyl, cycloalkyl, alkenyl, alkynyl, aryl, heterocycloalkyl, andheteroaryl; and

R for each instance is independently selected from the group consistingof hydrogen, alkyl, aryl, and heteroaryl.

In a fourth embodiment, provided herein is the compound of the firstaspect, wherein the compound has the Formula 4:

each of R³, R⁴, R⁵, R⁶, and R⁷ is independently selected from the groupconsisting of hydrogen, halide, nitrile, nitro, —OR, —NR₂, alkyl,cycloalkyl, alkenyl, alkynyl, aryl, heterocycloalkyl, and heteroaryl,wherein R is alkyl, aryl, or heteroaryl.

In a fifth embodiment, provided herein is the compound of the firstaspect, wherein the compound has the Formula 5:

wherein each of m and n is independently 1 or 2;

each of R¹ and R² for each instance is independently selected from thegroup consisting of hydrogen, halide, nitrile, nitro, —OR, —NR₂,—(C═O)R, —(C═O)OR, —(C═O)NR₂, —N(R)(C═O)R, —O(C═O)R, —N(R)(C═O)OR,—O(C═O)NR₂, alkyl, cycloalkyl, alkenyl, alkynyl, aryl, heterocycloalkyl,and heteroaryl;

R³, R⁴, R⁵, R⁶, and R⁷ for each instance is independently selected fromthe group consisting of hydrogen, halide, nitrile, nitro, —OR, —NR₂,—(C═O)R, —(C═O)OR, —(C═O)NR₂, —N(R)(C═O)R, —O(C═O)R, —N(R)(C═O)OR,—O(C═O)NR₂, alkyl, cycloalkyl, alkenyl, alkynyl, aryl, heterocycloalkyl,and heteroaryl; and

R for each instance is independently selected from the group consistingof hydrogen, alkyl, cycloalkyl, alkenyl, alkynyl, aryl,heterocycloalkyl, and heteroaryl; or two instances of R taken togetherform a 3-6 membered heterocycloalkyl.

In a sixth embodiment, provided herein is the compound of the fifthembodiment of the first aspect, wherein each of R⁶ and R⁷ for eachinstance is independently selected from the group consisting ofhydrogen, halide, —OR, alkyl, cycloalkyl, alkenyl, alkynyl, aryl,heterocycloalkyl, and heteroaryl.

In a seventh embodiment, provided herein is the compound of the sixthembodiment of the first aspect, wherein each of R³, R⁴, and R⁵ areindependently selected from hydrogen, —OR, —NR₂, alkyl, alkynyl, aryl,and heteroaryl; and R for each instance is independently aryl orheteroaryl.

In an eighth embodiment, provided herein is the compound of the firstaspect, wherein the compound has the Formula 6:

wherein each of m and n is independently 1 or 2;

each of t and u is independently 1, 2, or 3;

R¹ and R² for each instance is independently selected from the groupconsisting of hydrogen, halide, nitrile, nitro, —OR, —SR, —NR₂, —(C═O)R,—(C═O)OR, —(C═O)NR₂, —N(R)(C═O)R, —O(C═O)R, —N(R)(C═O)OR, —O(C═O)NR₂,—SO₂R, —SO₂NR₂, alkyl, cycloalkyl, alkenyl, alkynyl, aryl,heterocycloalkyl, and heteroaryl; or two instance of R¹ taken togetherform a 5-6 membered cycloalkyl, heterocycloalkyl, aryl, or heteroaryl;or two instance of R² taken together form a 5-6 membered cycloalkyl,heterocycloalkyl, aryl, or heteroaryl; or one instance of R¹ and oneinstance of R² taken together form a covalent bond; or one instance ofR² and one instance of R⁶ taken together form a covalent bond;

R⁶ and R⁷ for each instance is independently selected from the groupconsisting of hydrogen, halide, nitrile, nitro, —OR, —SR, —NR₂, —(C═O)R,—(C═O)OR, —(C═O)NR₂, —N(R)(C═O)R, —O(C═O)R, —N(R)(C═O)OR, —O(C═O)NR₂,—SO₂R, —SO₂NR₂, alkyl, cycloalkyl, alkenyl, alkynyl, aryl,heterocycloalkyl, and heteroaryl; or one instance of R⁴ and on instanceof R⁵ form a covalent bond; or one instance of R³ and one instance of R¹taken together form a covalent bond; or one instance of R³ and oneinstance of R⁴ taken together form a covalent bond; or one instance ofR¹ and one instance of R⁵ taken together form a covalent bond; or oneinstance of R² and one instance of R⁵ taken together form a covalentbond; or one instance of R² and one instance of R⁷ taken together form acovalent bond; or one instance of R⁶ and one instance of R⁷ takentogether form a covalent bond; and

R for each instance is independently selected from the group consistingof hydrogen, alkyl, cycloalkyl, alkenyl, alkynyl, aryl,heterocycloalkyl, and heteroaryl; or two instances of R taken togetherform a 3-6 membered heterocycloalkyl.

In a ninth embodiment, provided herein is the compound of the eighthembodiment of the first aspect, wherein each of R¹ and R² for eachinstance is independently selected from the group consisting ofhydrogen, halide, nitrile, nitro, —OR, —NR₂, alkyl, cycloalkyl, alkenyl,alkynyl, aryl, heterocycloalkyl, and heteroaryl;

each of R⁶ and R⁷ for each instance is independently selected from thegroup consisting of hydrogen, halide, nitrile, nitro, —OR, —SR, —NR₂,alkyl, cycloalkyl, alkenyl, alkynyl, aryl, heterocycloalkyl, andheteroaryl; and

R for each instance is independently selected from the group consistingof hydrogen, alkyl, cycloalkyl, alkenyl, alkynyl, aryl,heterocycloalkyl, and heteroaryl; or two instances of R taken togetherform a 3-6 membered heterocycloalkyl.

In a tenth embodiment, provided herein is the compound of the eighthembodiment of the first aspect, wherein the compound has Formula 7:

wherein each of R⁶ and R⁷ for each instance is independently selectedfrom the group consisting of hydrogen, halide, —OR, alkyl, cycloalkyl,alkenyl, alkynyl, aryl, heterocycloalkyl, and heteroaryl.

In an eleventh embodiment, provided herein is the compound of the firstaspect, wherein the compound has the Formula 8:

wherein each of R⁶ and R⁷ is independently selected from hydrogen andalkyl.

In a twelfth embodiment, provided herein is the compound of the eleventhembodiment of the first aspect, wherein each of R⁶ and R⁷ is methyl.

In a second aspect, provided herein is a method of preparing thecompound of the first aspect, the method comprising: contacting acompound of Formula 1a:

wherein each of Ar¹, Ar², Ar³, Ar⁴, and Ar⁵ is independently selectedfrom the group consisting of aryl and heteroaryl; and

M is lithium, sodium, MgBr, or a Zn species; with a compound of Formula1b:

wherein each of Ar⁶, and Ar⁷ is independently selected from the groupconsisting of aryl and heteroaryl; and X is a halide; thereby formingthe compound of the first aspect.

In a first embodiment of the second aspect, provided herein is themethod of the second aspect, wherein the compound of Formula 1a is:

and the compound of Formula 1b is:

In a third aspect, provided herein is a method for detecting a change ina physical-chemical parameter in a test sample comprising the compoundof the first aspect, the method comprising: providing the test sample;measuring the fluorescence emission of the test sample; comparing themeasured fluorescence emission of the test sample with the fluorescenceemission of a control sample comprising the compound of the first aspectin a ground state; and based on the difference in fluorescence emissionbetween the test sample and the control sample determine whether thereis a change in the physical-chemical parameter, wherein the ground stateis the fluorescence emission of the compound of the first aspect in theabsence of the physical-chemical parameter.

In a first embodiment of the third aspect, provided herein is the methodof the third aspect, wherein the physical-chemical parameter is at leastone parameter selected from the group consisting of the temperature ofthe test sample, the sheer force exerted on the test sample, theoxidation state of the test sample, the solvent in the test sample; andthe isotropic hydrostatic pressure of the test sample.

In a second embodiment of the third aspect, provided herein is themethod of the third aspect, wherein the compound has the formula:

In a fourth aspect, provided herein is an organic light emitting diode(OLED) comprising the compound of the first aspect.

In a first embodiment of the fourth aspect, provided herein the OLED ofthe fourth aspect, wherein the compound has the formula:

BRIEF DESCRIPTION OF THE FIGURES

The above and other objects and features of the present disclosure willbecome apparent from the following description of the disclosure, whentaken in conjunction with the accompanying drawings.

FIG. 1 depicts an exemplary synthetic route to AIEgen 1 in accordancewith certain embodiments described herein.

FIG. 2 depicts the ¹H NMR spectrum of AIEgen 1 in CDC₃.

FIG. 3 depicts the ¹³C NMR spectrum of AIEgen 1 in CDC₃.

FIG. 4 depicts the HR-MS spectrum of AIEgen 1.

FIG. 5 depicts (A) The molecular structure of AIEgen 1. (B) PL spectraof AIEgen 1 (1.0×10⁻⁵ M) in DMF-water mixtures, λ_(ex)=390 nm. (C) Plotof relative maximum emission peak intensity (α_(AIE)) at 500 nm versusf_(w) of the DMF/water mixture, where α_(AIE)=I/I₀, I=emission intensityand I₀=emission intensity in DMF solution. Inset: photos taken under 365nm UV light of AIEgen 1 in DMF-water mixtures.

FIG. 6 depicts the (A) PL spectra of AIEgen 1 measured in differentsolvents. (B) Linear correlation of the orientation polarization (Δf) ofsolvent with Stokes shift (v_(a)-v_(f)) for AIEgen 1 (R²=0.991). Inset:CIE chromaticity diagram showing the temperature dependence of the (x,y) color coordinates of AIEgen 1. Concentration: 1.0×10⁻⁵ M; λ_(ex)=390nm. Abbreviation: TEA=triethylamine, IPE=isopropyl ether, DEE=diethylether, EA=ethyl acetate, THF=tetrahydrofuran, DCM=dichloromethane,DMF=N,N′-dimethylformamide, ACN=acetonitrile.

FIG. 7 depicts Table 1 that includes photophysical properties of AIEgen1 in different solvents. ^(a)) v_(a) and v_(f) are the UV and PL peaksin different solvents, respectively; ^(b)) Stokes shift in differentsolvents; ^(c)) Orientation polarization; ^(d)) Absolute fluorescencequantum yield.

FIG. 8 depicts the natural transition orbitals (NTO) of the firstsinglet excited state. The contribution of the electronic transition tothe first singlet excitation state is about 99%.

FIG. 9 depicts the (A) temperature-dependent fluorescence spectra ofAIEgen 1 in THF solution (1×10⁻⁵ M; λ_(ex)=390 nm). (B) Plot of thecorresponding intensity ratio (λ₅₅₆/λ₅₉₆) with temperature (R²=0.988).

FIG. 10 depicts the temperature-dependent fluorescence spectra ofcompound AIEgen 1 in different solvents: (A) toluene, (B)dichloroethane, and (C) o-dichlorobenzene (1×10⁻⁵ M, λ_(ex)=390 nm).Inset: Photographs of fluorescence at different temperatures.

FIG. 11 depicts the (A) temperature-dependent fluorescence spectra and(B) plot of the corresponding intensity ratio (λ₅₃₅/λ₆₀₀) of AIEgen 1 intetraethylene glycol dimethyl ether with temperature (1×10⁻⁵ M,λ_(ex)=390 nm, R²=0.993). (C) CIE chromaticity diagram showing thetemperature dependence of the (x, y) color coordinates of AIEgen 1. (D)The gradient fluorescence of AIEgen 1 solution in a quartz tube.

FIG. 12 depicts the (A) Molecular structures of the ground state and theexcited state of AIEgen 1 based on TDDFT calculations at B3LYP/6-31G(d)level. (B) Simulated fluorescence spectra and (C) calculated potentialenergies of different conformations in the excited state of AIEgen 1.

FIG. 13 depicts the (A) PL spectra of AIEgen 1 before grinding, aftergrinding, and after treatment with dichloromethane vapor. λ_(ex)=390 nm.(B) PXRD patterns of AIEgen 1 at different states and (C) photographstaken under irradiation with 365 nm UV light. (D) Writing and erasing ofletters “AIE” on the filter paper using AIEgen 1 taken under UV light.

FIG. 14 depicts photos of pristine (left) and ground (right) samples ofAIEgen 1 taken under room and UV light irradiation.

FIG. 15 depicts (A) photos of AIEgen 1 powder taken under differentpressure. Fluorescent spectra of AIEgen 1 powder during (B) compressionand (C) decompression, via a diamond anvil cell (DAC). (D) Raman spectraof AIEgen 1 powder taken at different pressures. Excitation wavelengthwas 365 nm.

FIG. 16 depicts the recovery properties of AIEgen 1 powder via DAC.Excitation wavelength was 365 nm.

FIG. 17 depicts Raman spectra of AIEgen 1 powder under differentpressure values (A: compression; B: decompression). Excitationwavelength was 365 nm

FIG. 18 depicts Table 2 showing crystal data and parameters of datacollection and refinement for AIEgen 1.

FIG. 19 depicts (A) intermolecular interactions of AIEgen 1 (H atomsexcept those involved in interactions are omitted for clarity, distanceunit: Å). (B) Possible intermolecular charge transfer interactions ofAIEgen 1 (D: donor, A: acceptor). (C) Molecular packings of AIEgen 1.Carbon, nitrogen, boron and hydrogen atoms are shown as gray, blue, pinkand green.

FIG. 20 depicts the crystal structure of AIEgen 1(P1-P7: labels ofphenyl rings).

FIG. 21 depicts Table 3 That shows experimental and DFT calculationsimulated (B3LYP/6-31G(d)) Raman internal modes of AIEgen 1.Crystallographic data for the structures reported in this work have beendeposited with the Cambridge Crystallographic Data Centre assupplementary publication no. CCDC: 1884262.

FIG. 22 depicts (A) cyclic voltammogram (black line, THF/0.1 Mn-Bu₄NPF₆, 298 K at 0.1 V s¹) and (B) square-wave voltammogram curves(red line, f=10 Hz) of AIEgen 1.

FIG. 23 depicts (A and B) electrochromism and (C) electroluminochromismAIEgen 1 in THF/0.1 M n-Bu₄NPF₆. Inset: Photos of AIEgen 1 at differentoxidation states taken under (A and B) day light and (C) 365 nm UVlight.

FIG. 24 depicts Table 4 showing photophysical properties of AIEgen 1 atsolid state. ^(a)) The LUMO energy level was calculated from the HOMOenergy level according to the equation HOMO=LUMO−E_(g)(HOMO=−(4.8+E_(ox) ^(onset)) eV) and E_(g) was calculated from thelow-energy absorption onset in the absorption spectra according to theequation E_(g)=1240/λ_(onset). ^(b)) Solid state. ^(c)) Vacuum-depositedon a quartz substrate.

FIG. 25 depicts the thermogravimetric analysis (TGA) curve of AIEgen 1.

FIG. 26 depicts the (A) PL spectra (Inset: photo taken under 365 nm UVlight and its corresponding quantum yield value) and (B) UV spectra aswell as lifetime (C) of the film for AIEgen 1 obtained by vacuumevaporation.

FIG. 27 depicts the (A) EQE versus brightness curve (inset: EL spectrumat 10 mA cm⁻²), (B) Current density-voltage-luminance plot, (C)Voltage-dependent EL spectra and (D) CE and PE versus brightness curveof a EL device with a configuration of indium tin oxide(ITO)/1,4,5,8,9,11-hexaazatriphenylenehexacarbonitrile (HATCN) (5nm)/1,1-bis[(di-4-tolylamino)phenyl]cyclohexane (TAPC) (25 nm)/AIEgen 1(35 nm)/1,3,5-tri(m-pyridin-3-ylphenyl)benzene,1,3,5-Tris(3-pyridyl-3-phenyl)benzene TmPyPB (55 nm)/LiF (1 nm)/Al.

FIG. 28 depicts Table 5. Photophysical properties of AIEgen 1 at solidstate. ^(a)) The LUMO energy level was calculated from the HOMO energylevel according to the equation HOMO=LUMO−E_(g) (HOMO=−(4.8+E_(ox)^(onset)) eV) and E_(g) was calculated from the low-energy absorptiononset in the absorption spectra according to the equationE_(g)=1240/λ_(onset).^([4] b)) Solid state. ^(c)) Vacuum-deposited on aquartz substrate.

FIG. 29 depicts an exemplary OLED according to certain embodimentsdescribed herein.

FIG. 30 depicts the energy levels of an OLED comprising AIEgen 1(labeled 1 in the Figure) in accordance with certain embodimentsdescribed herein.

The figures are not necessarily drawn to scale.

DETAILED DESCRIPTION

The present disclosure generally relates to AIE-active small moleculescontaining TAB and amine units, which are responsive to multipleexternal stimuli including solvent, temperature, mechanical shearingforce, hydrostatic pressure and electric field. More specifically, thisnew material exhibits solvatochromism and a wide range ofthermoresponsive behavior with high upper limit, which can realize thevisualization of both marked and subtle environmental polarity change bythe dramatically amplified luminescence signal and macroscopic colorchange. Furthermore, it can respond to anisotropic shearing force andisotropic hydrostatic pressure with remarkable but contrastingluminescence conversion. Meanwhile, it was sensitive to externalelectric stimulus displaying reversibly three-color switchedelectrochromism and on-to-off electrochromic photoluminescence. Suchproperties allow the fabrication of a high-performance non-doped OLEDwith a high external quantum efficiency of 5.22%. The present systemfeaturing multi-stimulus responsive properties has application invarious real-life applications, including the visualization of marked orsubtle polarity change, wide-range liquid thermometer, security inks andpapers, electroswitchable electrochromic material for informationrecording, storage device and OLED.

Definitions

Throughout the application, where compositions are described as having,including, or comprising specific components, or where processes aredescribed as having, including, or comprising specific process steps, itis contemplated that compositions of the present teachings can alsoconsist essentially of, or consist of, the recited components, and thatthe processes of the present teachings can also consist essentially of,or consist of, the recited process steps.

In the application, where an element or component is said to be includedin and/or selected from a list of recited elements or components, itshould be understood that the element or component can be any one of therecited elements or components, or the element or component can beselected from a group consisting of two or more of the recited elementsor components. Further, it should be understood that elements and/orfeatures of a composition, an apparatus, or a method described hereincan be combined in a variety of ways without departing from the spiritand scope of the present teachings, whether explicit or implicit herein

The use of the terms “include,” “includes”, “including,” “have,” “has,”or “having” should be generally understood as open-ended andnon-limiting unless specifically stated otherwise.

The use of the singular herein includes the plural (and vice versa)unless specifically stated otherwise. In addition, where the use of theterm “about” is before a quantitative value, the present teachings alsoinclude the specific quantitative value itself, unless specificallystated otherwise. As used herein, the term “about” refers to a ±10%,±7%, ±5%, ±3%, ±1%, or ±0% variation from the nominal value unlessotherwise indicated or inferred.

It should be understood that the order of steps or order for performingcertain actions is immaterial so long as the present teachings remainoperable. Moreover, two or more steps or actions may be conductedsimultaneously.

As used herein, “halo”, “halide”, or “halogen” refers to fluoro, chloro,bromo, and iodo.

As used herein, “alkyl” refers to a straight-chain or branched saturatedhydrocarbon group. Examples of alkyl groups include methyl (Me), ethyl(Et), propyl (e.g., n-propyl and z′-propyl), butyl (e.g., n-butyl,z′-butyl, sec-butyl, tert-butyl), pentyl groups (e.g., n-pentyl,z′-pentyl, -pentyl), hexyl groups, and the like. In various embodiments,an alkyl group can have 1 to 40 carbon atoms (i.e., C₁-C₄₀ alkyl group),for example, 1-30 carbon atoms (i.e., C₁-C₃₀ alkyl group). In someembodiments, an alkyl group can have 1 to 6 carbon atoms, and can bereferred to as a “lower alkyl group.” Examples of lower alkyl groupsinclude methyl, ethyl, propyl (e.g., n-propyl and z′-propyl), and butylgroups (e.g., n-butyl, z′-butyl, sec-butyl, tert-butyl). In someembodiments, alkyl groups can be substituted as described herein. Analkyl group is generally not substituted with another alkyl group, analkenyl group, or an alkynyl group.

The term “aralkyl” is art-recognized and refers to an alkyl groupsubstituted with an aryl group (e.g., an aromatic or heteroaromaticgroup).

As used herein, “cycloalkyl” by itself or as part of another substituentmeans, unless otherwise stated, a monocyclic hydrocarbon having between3-12 carbon atoms in the ring system and includes hydrogen, straightchain, branched chain, and/or cyclic substituents. Exemplary cycloalkylsinclude cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl,and the like.

As used herein, “alkenyl” refers to a straight-chain or branched alkylgroup having one or more carbon-carbon double bonds. Examples of alkenylgroups include ethenyl, propenyl, butenyl, pentenyl, hexenyl,butadienyl, pentadienyl, hexadienyl groups, and the like. The one ormore carbon-carbon double bonds can be internal (such as in 2-butene) orterminal (such as in 1-butene). In various embodiments, an alkenyl groupcan have 2 to 40 carbon atoms (i.e., C₂-C₄₀ alkenyl group), for example,2 to 20 carbon atoms (i.e., C₂-C₂₀ alkenyl group). In some embodiments,alkenyl groups can be substituted as described herein. An alkenyl groupis generally not substituted with another alkenyl group, an alkyl group,or an alkynyl group.

As used herein, a “fused ring” or a “fused ring moiety” refers to apolycyclic ring system having at least two rings where at least one ofthe rings is aromatic and such aromatic ring (carbocyclic orheterocyclic) has a bond in common with at least one other ring that canbe aromatic or non-aromatic, and carbocyclic or heterocyclic. Thesepolycyclic ring systems can be highly p-conjugated and optionallysubstituted as described herein.

As used herein, “heteroatom” refers to an atom of any element other thancarbon or hydrogen and includes, for example, nitrogen, oxygen, silicon,sulfur, phosphorus, and selenium.

As used herein, “aryl” refers to an aromatic monocyclic hydrocarbon ringsystem or a polycyclic ring system in which two or more aromatichydrocarbon rings are fused (i.e., having a bond in common with)together or at least one aromatic monocyclic hydrocarbon ring is fusedto one or more cycloalkyl and/or cycloheteroalkyl rings. An aryl groupcan have 6 to 24 carbon atoms in its ring system (e.g., C₆-C₂₄ arylgroup), which can include multiple fused rings. In some embodiments, apolycyclic aryl group can have 8 to 24 carbon atoms. Any suitable ringposition of the aryl group can be covalently linked to the definedchemical structure. Examples of aryl groups having only aromaticcarbocyclic ring(s) include phenyl, 1-naphthyl (bicyclic), 2-naphthyl(bicyclic), anthracenyl (tricyclic), phenanthrenyl (tricyclic),pentacenyl (pentacyclic), and like groups. Examples of polycyclic ringsystems in which at least one aromatic carbocyclic ring is fused to oneor more cycloalkyl and/or cycloheteroalkyl rings include, among others,benzo derivatives of cyclopentane (i.e., an indanyl group, which is a5,6-bicyclic cycloalkyl/aromatic ring system), cyclohexane (i.e., atetrahydronaphthyl group, which is a 6,6-bicyclic cycloalkyl/aromaticring system), imidazoline (i.e., a benzimidazolinyl group, which is a5,6-bicyclic cycloheteroalkyl/aromatic ring system), and pyran (i.e., achromenyl group, which is a 6,6-bicyclic cycloheteroalkyl/aromatic ringsystem). Other examples of aryl groups include benzodioxanyl,benzodioxolyl, chromanyl, indolinyl groups, and the like. In someembodiments, aryl groups can be optionally substituted as describedherein. The aryl ring may be substituted at one or more positions withsuch substituents as described herein, as for example, halogen, alkyl,aralkyl, alkenyl, alkynyl, cycloalkyl, hydroxyl, amino, nitro,sulfhydryl, imino, amido, phosphonate, phosphinate, carbonyl, carboxyl,silyl, ether, alkylthio, sulfonyl, ketone, aldehyde, ester, aheterocyclyl, an aromatic or heteroaromatic moiety, —CF₃, —CN, or thelike. In some embodiments, an aryl group can have one or more halogensubstituents, and can be referred to as a “haloaryl” group. Perhaloarylgroups, i.e., aryl groups where all of the hydrogen atoms are replacedwith halogen atoms (e.g., —C₆F₅), are included within the definition of“haloaryl.” In certain embodiments, an aryl group is substituted withanother aryl group and can be referred to as a biaryl group. Each of thearyl groups in the biaryl group can be optionally substituted asdisclosed herein.

As used herein, “heteroaryl” refers to an aromatic monocyclic ringsystem containing at least one ring heteroatom selected from oxygen (O),nitrogen (N), sulfur (S), silicon (Si), and selenium (Se) or apolycyclic ring system where at least one of the rings present in thering system is aromatic and contains at least one ring heteroatom.Polycyclic heteroaryl groups include those having two or more heteroarylrings fused together, as well as those having at least one monocyclicheteroaryl ring fused to one or more aromatic carbocyclic rings,non-aromatic carbocyclic rings, and/or non-aromatic cycloheteroalkylrings. A heteroaryl group, as a whole, can have, for example, 5 to 24ring atoms and contain 1-5 ring heteroatoms (i.e., 5-20 memberedheteroaryl group). The heteroaryl group can be attached to the definedchemical structure at any heteroatom or carbon atom that results in astable structure. Generally, heteroaryl rings do not contain O—O, S—S,or S—O bonds. However, one or more N or S atoms in a heteroaryl groupcan be oxidized (e.g., pyridine N-oxide thiophene S-oxide, thiopheneS,S-dioxide). Examples of heteroaryl groups include, for example, the 5-or 6-membered monocyclic and 5-6 bicyclic ring systems shown below:where T is O, S, NH, N-alkyl, N-aryl, N-(arylalkyl) (e.g., N-benzyl),SiH₂, SiH(alkyl), Si(alkyl)₂, SiH(arylalkyl), Si(arylalkyl)₂, orSi(alkyl)(arylalkyl). Examples of such heteroaryl rings includepyrrolyl, furyl, thienyl, pyridyl, pyrimidyl, pyridazinyl, pyrazinyl,triazolyl, tetrazolyl, pyrazolyl, imidazolyl, isothiazolyl, thiazolyl,thiadiazolyl, isoxazolyl, oxazolyl, oxadiazolyl, indolyl, isoindolyl,benzofuryl, benzothienyl, quinolyl, 2-methylquinolyl, isoquinolyl,quinoxalyl, quinazolyl, benzotriazolyl, benzimidazolyl, benzothiazolyl,benzisothiazolyl, benzisoxazolyl, benzoxadiazolyl, benzoxazolyl,cinnolinyl, 1H-indazolyl, 2H-indazolyl, indolizinyl, isobenzofuyl,naphthyridinyl, phthalazinyl, pteridinyl, purinyl, oxazolopyridinyl,thiazolopyridinyl, imidazopyridinyl, furopyridinyl, thienopyridinyl,pyridopyrimidinyl, pyridopyrazinyl, pyridopyridazinyl, thienothiazolyl,thienoxazolyl, thienoimidazolyl groups, and the like. Further examplesof heteroaryl groups include 4,5,6,7-tetrahydroindolyl,tetrahydroquinolinyl, benzothienopyridinyl, benzofuropyridinyl groups,and the like. In some embodiments, heteroaryl groups can be optionallysubstituted as described herein. The heterocyclic ring may besubstituted at one or more positions with such substituents as describedherein, as for example, halogen, alkyl, aralkyl, alkenyl, alkynyl,cycloalkyl, hydroxyl, amino, nitro, sulfhydryl, imino, amido,phosphonate, phosphinate, carbonyl, carboxyl, silyl, ether, alkylthio,sulfonyl, ketone, aldehyde, ester, a heterocyclyl, an aromatic orheteroaromatic moiety, —CF₃, —CN, or the like.

The term “optionally substituted” refers to a chemical group, such asalkyl, cycloalkyl, aryl, heteroaryl, and the like, wherein one or morehydrogen may be replaced with a with a substituent as described herein,for example, halogen, azide, alkyl, aralkyl, alkenyl, alkynyl,cycloalkyl, hydroxyl, alkoxyl, amino, nitro, sulfhydryl, imino, amido,phosphonate, phosphinate, carbonyl, carboxyl, silyl, ether, alkylthio,sulfonyl, sulfonamido, ketone, aldehyde, ester, heterocyclyl, aromaticor heteroaromatic moieties, —CF₃, —CN, or the like

The representation “I” as used herein in connection to chemical a groupor moiety is intended to represent the covalent bond that theaforementioned chemical group or moiety is covalently bonded to anotherchemical group or moiety.

The phrase “aggregation-induced emission” or “AIE” as used herein refersto the enhancement of light-emission by a fluorescent compound uponaggregation in the amorphous or crystalline (solid) states of thefluorescent compound, whereas the fluorescent compound exhibits weak orsubstantially no emission in dilute solutions.

The term “λ_(ex)” as used herein refers to the excitation wavelength.

The term “λ_(em)” as used herein refers to the emission wavelength.

Inspired by the distinctive stimuli-responsive behaviors of naturalcreatures, a simple but versatile class of aggregation-induced emissionluminogen (AIEgen) compounds with donor-acceptor structure andpronounced intramolecular charge transfer property, exemplified byAIEgen 1, was developed. The compounds described herein can exhibitsolvatochromism and a wide range of thermoresponsive behavior with highupper limit, which can realize the visualization of both marked andsubtle environmental polarity change by the dramatically amplifiedluminescence signal and macroscopic color change. Furthermore, thecompounds described herein can respond to numerous environmental orphysical-chemical changes, such as anisotropic shearing force andisotropic hydrostatic pressure with remarkable but contrastingluminescence conversion due to the distinct disturbance of the weakintermolecular interactions and charge transfer processes.

The compounds described herein can also be sensitive to externalelectric stimulus displaying reversibly three-color switchedelectrochromism and on-to-off electrochromic photoluminescence. Suchproperty allowed the fabrication of high-performance non-doped OLED witha high external quantum efficiency of 5.22%. The present results mayoffer an efficient guideline for multifunctional molecular design andprovide an important step forward in expanding the real-lifeapplications of AIE-active materials.

Provided herein is a compound of Formula 1:

wherein each of Ar¹, Ar², Ar³, Ar⁴, Ar⁵, Ar⁶, and Ar⁷ is independentlyselected from the group consisting of aryl and heteroaryl.

In certain embodiments, the Ar⁴—N nitrogen is covalently bonded to Ar⁵in a position in which the lone pair on the said nitrogen is conjugatedthrough the pi system of Ar⁵ with the boron.

In certain embodiments, each of Ar¹, Ar², Ar³, Ar⁴, Ar⁵, Ar⁶, and Ar⁷ isindependently optionally substituted aryl or heteroaryl. Each of Ar¹,Ar², Ar³, Ar⁴, Ar⁵, Ar⁶, and Ar⁷ can independently be optionallysubstituted with a substituent selected from the group consisting ofhydrogen, halide, nitrile, nitro, —OR, —SR, —NR₂, —(C═O)R, —(C═O)OR,—(C═O)NR₂, —N(R)(C═O)R, —O(C═O)R, —N(R)(C═O)OR, —O(C═O)NR₂, —SO₂R,—SO₂NR₂, alkyl, cycloalkyl, alkenyl, alkynyl, aryl, heterocycloalkyl,and heteroaryl, wherein R is hydrogen, alkyl, cycloalkyl, alkenyl,alkynyl, aryl, heterocycloalkyl, and heteroaryl; or two instances of Rtaken together form a 3-6 membered heterocycloalkyl. Each of Ar¹, Ar²,Ar³, Ar⁴, Ar⁵, Ar⁶, and Ar⁷ can independently be optionally substitutedwith 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 substituents.

In certain embodiments, each of Ar¹, Ar², Ar³, Ar⁴, Ar⁵, Ar⁶, and Ar⁷ isindependently optionally substituted phenyl.

In certain embodiments, the compound has the Formula 2:

wherein each of m and n is independently 1, 2, 3, or 4;

R¹ and R² for each instance is independently selected from the groupconsisting of hydrogen, halide, nitrile, nitro, —OR, —SR, —NR₂, —(C═O)R,—(C═O)OR, —(C═O)NR₂, —N(R)(C═O)R, —O(C═O)R, —N(R)(C═O)OR, —O(C═O)NR₂,—SO₂R, —SO₂NR₂, alkyl, cycloalkyl, alkenyl, alkynyl, aryl,heterocycloalkyl, and heteroaryl; or two instance of R¹ taken togetherform a 5-6 membered cycloalkyl, heterocycloalkyl, aryl, or heteroaryl;or two instance of R² taken together form a 5-6 membered cycloalkyl,heterocycloalkyl, aryl, or heteroaryl; or one instance of R¹ and oneinstance of R² taken together form a covalent bond; and

R for each instance is independently selected from the group consistingof hydrogen, alkyl, cycloalkyl, alkenyl, alkynyl, aryl,heterocycloalkyl, and heteroaryl; or two instances of R taken togetherform a 3-6 membered heterocycloalkyl.

In certain embodiments of the compound of Formula 2, each of m and n is1 or 2; and R¹ and R² for each instance is independently selected fromthe group consisting of hydrogen, halide, nitrile, nitro, —OR, —SR,—NR₂, alkyl, cycloalkyl, alkenyl, alkynyl, aryl, heterocycloalkyl, andheteroaryl.

In certain embodiments of the compound of Formula 2, each of Ar¹, Ar²,Ar⁴, Ar⁶, and Ar⁷ is independently aryl. In certain embodiments, each ofAr¹, Ar², Ar⁴, Ar⁶, and Ar⁷ is independently optionally substitutedphenyl.

In certain embodiments, the compound has the Formula 3:

wherein each of m and n is independently 1, 2, 3, or 4;

each of o, p, q, t, and u is independently 1, 2, 3, 4, or 5;

R¹ and R² for each instance is independently selected from the groupconsisting of hydrogen, halide, nitrile, nitro, —OR, —SR, —NR₂, —(C═O)R,—(C═O)OR, —(C═O)NR₂, —N(R)(C═O)R, —O(C═O)R, —N(R)(C═O)OR, —O(C═O)NR₂,—SO₂R, —SO₂NR₂, alkyl, cycloalkyl, alkenyl, alkynyl, aryl,heterocycloalkyl, and heteroaryl; or two instance of R¹ taken togetherform a 5-6 membered cycloalkyl, heterocycloalkyl, aryl, or heteroaryl;or two instance of R² taken together form a 5-6 membered cycloalkyl,heterocycloalkyl, aryl, or heteroaryl; or one instance of R¹ and oneinstance of R² taken together form a covalent bond;

R³, R⁴, R⁵, R⁶, and R⁷ for each instance is independently selected fromthe group consisting of hydrogen, halide, nitrile, nitro, —OR, —SR,—NR₂, —(C═O)R, —(C═O)OR, —(C═O)NR₂, —N(R)(C═O)R, —O(C═O)R, —N(R)(C═O)OR,—O(C═O)NR₂, —SO₂R, —SO₂NR₂, alkyl, cycloalkyl, alkenyl, alkynyl, aryl,heterocycloalkyl, and heteroaryl; or one instance of R⁴ and on instanceof R⁵ form a covalent bond; or one instance of R³ and one instance of R¹taken together form a covalent bond; or one instance of R³ and oneinstance of R⁴ taken together form a covalent bond; or one instance ofR¹ and one instance of R⁵ taken together form a covalent bond; or oneinstance of R² and one instance of R⁵ taken together form a covalentbond; or one instance of R² and one instance of R⁷ taken together form acovalent bond; or one instance of R⁶ and one instance of R⁷ takentogether form a covalent bond; and

R for each instance is independently selected from the group consistingof hydrogen, alkyl, cycloalkyl, alkenyl, alkynyl, aryl,heterocycloalkyl, and heteroaryl; or two instances of R taken togetherform a 3-6 membered heterocycloalkyl.

In certain embodiments of the compound of Formula 3, each of m and n is1; and each of o, p, q, t, and u is 1.

In certain embodiments, the compound has Formula 3a:

wherein each of u and t is independently 1, 2, or 3;

R¹, R², R³, R⁴, R⁵, R⁶, and R⁷ for each instance is independentlyselected from the group consisting of hydrogen, halide, nitrile, nitro,—OR, —SR, —NR₂, —(C═O)R, —(C═O)OR, —(C═O)NR₂, —N(R)(C═O)R, —O(C═O)R,—N(R)(C═O)OR, —O(C═O)NR₂, —SO₂R, —SO₂NR₂, alkyl, cycloalkyl, alkenyl,alkynyl, aryl, heterocycloalkyl, and heteroaryl; and R for each instanceis independently selected from the group consisting of hydrogen, alkyl,cycloalkyl, alkenyl, alkynyl, aryl, heterocycloalkyl, and heteroaryl; ortwo instances of R taken together form a 3-6 membered heterocycloalkyl.

In certain embodiments of the compound of Formula 3a, R for eachinstance is independently selected from the group consisting ofhydrogen, alkyl, cycloalkyl, alkenyl, alkynyl, aryl, heterocycloalkyl,and heteroaryl.

In certain embodiments of the compound of Formula 3a, each of R¹ and R²is independently selected from the group consisting of hydrogen, halide,nitrile, nitro, —OR, —NR₂, alkyl, cycloalkyl, alkenyl, alkynyl, aryl,heterocycloalkyl, and heteroaryl. In certain embodiments of the compoundof Formula 3a, R¹ and R² are hydrogen.

In certain embodiments of the compound of Formula 3a, each of R³, R⁴,R⁵, R⁶, and R⁷ is independently selected from the group consisting ofhydrogen, halide, nitrile, nitro, —OR, —NR₂, alkyl, cycloalkyl, alkenyl,alkynyl, aryl, heterocycloalkyl, and heteroaryl.

In certain embodiments of the compound of Formula 3a, R¹ and R² arehydrogen; R³, R⁴, R⁵, R⁶, and R⁷ for each instance is independentlyselected from hydrogen, —OR, —SR, —NR₂, alkyl, cycloalkyl, alkenyl,alkynyl, aryl, heterocycloalkyl, and heteroaryl; and R for each instanceis independently selected from the group consisting of hydrogen, alkyl,cycloalkyl, alkenyl, alkynyl, aryl, heterocycloalkyl, and heteroaryl.

In certain embodiments, the compound has Formula 4:

each of R³, R⁴, R⁵, R⁶, and R⁷ is independently selected from the groupconsisting of hydrogen, halide, nitrile, nitro, —OR, —NR₂, alkyl,cycloalkyl, alkenyl, alkynyl, aryl, heterocycloalkyl, and heteroaryl,wherein R is alkyl, aryl, or heteroaryl.

In certain embodiments of the compound of Formula 4, each of R³, R⁴, R⁵,R⁶, and R⁷ is independently selected from the group consisting ofhydrogen, —OR, alkyl, alkenyl, alkynyl, aryl, and heteroaryl, wherein Ris alkyl, aryl, or heteroaryl.

In certain embodiments, the compound has Formula 5:

wherein each of m and n is independently 1 or 2;

each of R¹ and R² is independently selected from the group consisting ofhydrogen, halide, nitrile, nitro, —OR, —NR₂, —(C═O)R, —(C═O)OR,—(C═O)NR₂, —N(R)(C═O)R, —O(C═O)R, —N(R)(C═O)OR, —O(C═O)NR₂, alkyl,cycloalkyl, alkenyl, alkynyl, aryl, heterocycloalkyl, and heteroaryl;

each of R³, R⁴, R⁵, R⁶, and R⁷ is independently selected from the groupconsisting of hydrogen, halide, nitrile, nitro, —OR, —NR₂, —(C═O)R,—(C═O)OR, —(C═O)NR₂, —N(R)(C═O)R, —O(C═O)R, —N(R)(C═O)OR, —O(C═O)NR₂,alkyl, cycloalkyl, alkenyl, alkynyl, aryl, heterocycloalkyl, andheteroaryl; and

R for each instance is independently selected from the group consistingof hydrogen, alkyl, cycloalkyl, alkenyl, alkynyl, aryl,heterocycloalkyl, and heteroaryl; or two instances of R taken togetherform a 3-6 membered heterocycloalkyl.

In certain embodiments of the compound has Formula 5, each of R¹ and R²for each instance is independently selected from the group consisting ofhydrogen, halide, nitrile, nitro, alkyl, cycloalkyl, alkenyl, alkynyl,aryl, heterocycloalkyl, and heteroaryl.

In certain embodiments of the compound of Formula 5, each of R³, R⁴, R⁵,R⁶, and R⁷ is independently selected from the group consisting ofhydrogen, halide, nitrile, nitro, —OR, —NR₂, alkyl, cycloalkyl, alkenyl,alkynyl, aryl, heterocycloalkyl, and heteroaryl.

In certain embodiments of the compound has Formula 5, each of R⁶ and R⁷is hydrogen, alkyl, cycloalkyl, aryl, or heteroaryl.

In certain embodiments of the compound has Formula 5, each of R¹ and R²is hydrogen; each of R³, R⁴, and R⁵ is independently selected from thegroup consisting of hydrogen, halide, nitrile, nitro, —OR, —NR₂, alkyl,cycloalkyl, alkenyl, alkynyl, aryl, heterocycloalkyl, and heteroaryl;and each of R⁶ and R⁷ is hydrogen, alkyl, cycloalkyl, aryl, orheteroaryl.

In certain embodiments, the compound has Formula 6:

wherein each of m and n is independently 1 or 2;

each of t and u is independently 1, 2, or 3;

R¹ and R² for each instance is independently selected from the groupconsisting of hydrogen, halide, nitrile, nitro, —OR, —SR, —NR₂, —(C═O)R,—(C═O)OR, —(C═O)NR₂, —N(R)(C═O)R, —O(C═O)R, —N(R)(C═O)OR, —O(C═O)NR₂,—SO₂R, —SO₂NR₂, alkyl, cycloalkyl, alkenyl, alkynyl, aryl,heterocycloalkyl, and heteroaryl; or two instance of R¹ taken togetherform a 5-6 membered cycloalkyl, heterocycloalkyl, aryl, or heteroaryl;or two instance of R² taken together form a 5-6 membered cycloalkyl,heterocycloalkyl, aryl, or heteroaryl; or one instance of R¹ and oneinstance of R² taken together form a covalent bond; or one instance ofR² and one instance of R⁶ taken together form a covalent bond;

R⁶ and R⁷ for each instance is independently selected from the groupconsisting of hydrogen, halide, nitrile, nitro, —OR, —SR, —NR₂, —(C═O)R,—(C═O)OR, —(C═O)NR₂, —N(R)(C═O)R, —O(C═O)R, —N(R)(C═O)OR, —O(C═O)NR₂,—SO₂R, —SO₂NR₂, alkyl, cycloalkyl, alkenyl, alkynyl, aryl,heterocycloalkyl, and heteroaryl; or one instance of R⁴ and on instanceof R⁵ form a covalent bond; or one instance of R³ and one instance of R¹taken together form a covalent bond; or one instance of R³ and oneinstance of R⁴ taken together form a covalent bond; or one instance ofR¹ and one instance of R⁵ taken together form a covalent bond; or oneinstance of R² and one instance of R⁵ taken together form a covalentbond; or one instance of R² and one instance of R⁷ taken together form acovalent bond; or one instance of R⁶ and one instance of R⁷ takentogether form a covalent bond; and

R for each instance is independently selected from the group consistingof hydrogen, alkyl, cycloalkyl, alkenyl, alkynyl, aryl,heterocycloalkyl, and heteroaryl; or two instances of R taken togetherform a 3-6 membered heterocycloalkyl.

In certain embodiments, the compound has Formula 7:

wherein each of m and n is independently 1 or 2; each of Ar¹, Ar², andAr⁴ is independently selected from the group consisting of aryl andheteroaryl; R¹ and R² for each instance is independently selected fromthe group consisting of hydrogen alkyl, cycloalkyl, alkenyl, alkynyl,aryl, heterocycloalkyl, and heteroaryl; each of R⁶ and R⁷ for eachinstance is independently selected from the group consisting ofhydrogen, halide, —OR, alkyl, cycloalkyl, alkenyl, alkynyl, aryl,heterocycloalkyl, and heteroaryl.

In certain embodiments of the compound of Formula 7, Ar¹, Ar², and Ar⁴is independently optionally substituted phenyl. In certain embodimentsof the compound of Formula 7, each R¹ and R² is hydrogen; each of Ar¹,Ar², and Ar⁴ is independently optionally substituted phenyl; and each ofR⁶ and R⁷ for each instance is independently selected from the groupconsisting of hydrogen, alkyl, aryl, and heteroaryl.

In certain embodiments, the compound has the Formula 8:

wherein each of R⁶ and R⁷ is independently selected from hydrogen andalkyl. In certain embodiments, each of R⁶ and R⁷ is C₁-C₆ alkyl. Incertain embodiments, each of R⁶ and R⁷ is methyl.

In certain embodiments, the compound is selected from the groupconsisting of:

wherein z is 0-12.

The compounds described herein can be covalently conjugated to atargeting agent. The targeting agent can be an antibody, an antibodyfragment (such as Fab, Fab′, F(ab′)₂, and Fv), single chain (ScFv)) apeptide, an aptamer, or a small molecule that is capable of selectivelybinding to a target of interest, such as a carbohydrate, polynucleotide,lipid, polypeptide, protein, small molecule, cellular receptor, etc.

The compound described herein can be directly attached to the targetingagent or attached to the targeting agent via a chemical linker. Ininstances where the compound described herein is attached to thetargeting agent via a linker, any linker in the art can be used toattach the compound described herein and the targeting agent. Theselection of the linker is well within the skill of a person skilled inthe art. Exemplary linkers include, but are not limited to polyethyleneglycol linkers, alkyl amides, alkyl esters, alkyl sulfonamides, alkylsulfones, alkanes, aryl amides, aryl esters, aryl sulfonamides, arylsulfones, aryl, and combinations thereof. The linker can be covalentlyattached to the targeting agent by an amide bond, ester bond, sulfonebond, sulfur bond, a bond to a trizole, urea bond, ether bond or thelike.

In certain embodiments, the compounds described herein comprise alinker. The linker can be covalently attached to the compounds describedherein at any at position of the compound subject to the rules ofvalency. In certain embodiments of any of the compounds describedherein, R¹, R², R³, R⁴, R⁵, R⁶, or R⁷ is the linker, wherein the linkeris represented by the formula: -Q¹(CH₂)_(v)Y², wherein v is a wholenumber selected between 0-10; Q¹ is a bond, —O—, —(C═O)O—, —O(C═O)—,—(C═O)NH—, or —NH(C═O)—; and Y² is —NH₂, —OH, —SH, —CO₂H, alkyne, azide,or N-maleimide; or the linker is represented by the formula:—(OCH₂CH₂)_(v)Y² or —(CH₂CH₂)_(v)(CH₂)_(w)Y², wherein each of v and w isindependently 1-10; and Y² is —NH₂, —OH, —SH, —CO₂H, alkyne, azide, orN-maleimide.

The compounds described herein can be readily prepared using well knownorganic synthetic methodologies. Synthetic chemists can devise numeroussynthetic routes for preparing the compound of Formula 1 usingretrosynthetic analysis.

In one exemplary approach the carbon boron covalent bond can be formedin the final step of the synthetic methodology as shown below:

wherein Ar¹, Ar², Ar³, Ar⁴, Ar⁵, Ar⁶, and Ar⁷ are as defined herein.

This synthetic transformation can be accomplished any number of ways.For example, metal catalyzed (e.g., palladium) cross coupling of atetraryl diborane (e.g., wherein Y¹=—B(Ar⁶)(Ar⁷)) and a suitablyfunctionalized aryl or heteroaryl halide, tosylate, mesylate,trifluormesylate, or other suitable leaving group (e.g., whereinX¹=halide, tosylate, mesylate, trifluormesylate, and the like). Thisapproach suffers from the waste of half the tetraryldiborane, as onlyone diaryl borane is coupled in the reaction.

Alternatively, a substitution reaction can be used to couple an aryl orheteroaryl active metal (e.g., wherein X¹ is Li, Na, MgBr, or a zincspecies, such as Znalkyl, Znhalide, or

and Y¹ is a leaving group (e.g., wherein Y¹ is halide or alkoxide).

In another aspect, provided herein is a method for preparing thecompound of Formula 1, the method comprising: the method comprising:contacting a compound of Formula 1a:

wherein each of Ar¹, Ar², Ar³, Ar⁴, and Ar⁵ is independently selectedfrom the group consisting of aryl and heteroaryl; and M is lithium,sodium, MgBr, or a Zn species; with a compound of Formula 1b:

wherein each of Ar⁶, and Ar⁷ is independently selected from the groupconsisting of aryl and heteroaryl; and X is a halide; thereby formingthe compound Formula 1.

Any of the compounds described herein can be prepared in a similarfashion. For example, AIEgen 1 can be prepared when the compound ofFormula 1a is:

and the compound of Formula 1b is:

An exemplary synthesis of AIEgen 1 is depicted in FIG. 1 in which thePrecursor 1 undergoes metal-halogen exchange to generate a reactivearyl-lithium intermediate, compound of Formula 1a, which then undergoesa substitution reaction with dimesitylboron fluoride thereby formingAIEgen 1. As detailed in the examples below, AIEgen 1 was facilelyprepared in a high yield of 79% through a simple one-step reaction alongthe synthetic route as presented in FIG. 1 in the SupportingInformation. The product was well characterized by NMR andhigh-resolution mass spectroscopy with satisfactory results (FIGS. 2-4).The structure of 1 was further confirmed by single crystal X-raydiffraction (details see below) and the associated data was summarizedin Table 1 (FIG. 7).

A person of ordinary skill in the art can readily conceive of thechemical structures of starting materials for preparing any of thecompounds described herein based on the teachings provided herein andgeneral knowledge in the art.

The step of contacting the compound of Formula 1a and the compound ofFormula 1b can be conducted in relatively unreactive aprotic solvents.Exemplary solvents include, but are not limited to ethers, aromatics,and combinations thereof. Suitable ethers include, but are not limitedto diethyl ether, tetrahydrofuran, 2-methyltetrahydrofuran,tetrahydropyran, dioxane, 1,2,-dimethoxyether (DME), tert-butyl methylether, and the like. Suitable aromatics include, but are not limited to,benzene, toluene, xylenes, and the like.

The step of contacting the compound of Formula 1a and the compound ofFormula 1b can be first be conducted at a temperature in the range of−100° C. to 20° C. and then optionally be allowed to warm to roomtemperature. In certain embodiments, the step of contacting the compoundof Formula 1a and the compound of Formula 1b can first be conducted at atemperature in the range of −100° C. to 20° C.; −100° C. to 10° C.;−100° C. to 0° C.; −90° C. to 0° C.; −80° C. to 0° C.; −80° C. to −10°C.; −80° C. to −20° C.; −80° C. to −30° C.; or −80° C. to −40° C.; −100°C. to 40° C.; −60° C. to 40° C.; −100° C. to 50° C.; −90° C. to 80° C.;and then allowed to optionally warm to room temperature.

As described in greater detail in this disclosure, the compoundsdescribed herein can exhibit multi-stimuli responsive fluorescentemissions. Such properties enable the use of the compound describedherein as sensors that are responsive to changes in a physical-chemicalparameter.

Thus in another aspect, provided herein is a method for detecting achange in a physical-chemical parameter in a test sample comprising thecompound described herein, the method comprising: providing the testsample; measuring the fluorescence emission of the test sample;comparing the measured fluorescence emission of the test sample with thefluorescence emission of a control sample comprising the compounddescribed herein in a ground state; and based on the difference influorescence emission between the test sample and the control sampledetermine whether there is a change in the physical-chemical parameter,wherein the ground state is the fluorescence emission of the compounddescribed herein in the absence of the physical-chemical parameter.

In certain embodiments, the physical-chemical parameter is at least oneparameter selected from the group consisting of the temperature of thetest sample, the sheer force exerted on the test sample, the oxidationstate of the test sample, the solvent in the test sample; the solventcomposition of the test sample; and the isotropic hydrostatic pressureof the test sample.

The multi-stimuli responsive emissive behavior of the compoundsdescribed herein have numerous applications, such as in liquidthermometers, security inks and papers, electroswitchable electrochromicmaterial for information recording, storage devices and OLED.

The difference in fluorescence emission can be a change in the emissionwavelength, change in emission intensity, or a combination thereof.

The EL properties of the compounds described herein can be particularlyuseful in the fabrication of luminescent devices, such as variouslyconfigured OLEDs. OLEDs that can be fabricated using the compound ofFormula I include from very simple structures having a single anode andcathode (e.g., monolayer OLEDs) to more complex devices, such as 2-layeror multilayer heterostructure configurations.

In certain embodiments, the OLED comprises an anode, a cathode, and alight emissive layer disposed between the anode and the cathode. Incertain embodiments the OLED further comprises a hole-transport layer.

In certain embodiments, the OLED has the structure shown in FIG. 29.OLED 100 contains an anode 110, a hole-injection layer 120, ahole-transport layer 130, a light-emitting layer 140, anelectron-transport layer 150, an electron-injection layer 160 and acathode 170. The light-emitting layer 140 can comprises the compound ofFormula I as a thin film. In some other embodiments, there are optionallayers on either side of the light-emitting layer 140.

In certain embodiments, the electron-injection layer 160 can besubdivided into two or more sublayers (not shown). In one illustrativeexample of the OLED, the electron-injection layer 170 is further dividedinto two sublayers, a first electron-injection layer adjacent to theelectron-transport layer 150 and a second electron-injection layerlocated between the first electron-injection layer and the cathode.

In certain embodiments, the hole-injection layer 120 can be subdividedinto two or more sublayers (not shown). In one illustrative example ofthe OLED device, the hole-injection layer 120 is further divided intotwo sublayers, a first hole-injection layer adjacent to thehole-transport layer 130 and a second hole-injection layer locatedbetween the first hole-injection layer and the anode.

In certain embodiments, there is a hole-blocking layer between thelight-emitting layer 140 and the electron-transport layer 150 (notshown).

The OLED can be configured such that the EL emission of the anode oralternatively through the cathode. When the EL emission occurs throughthe anode, the anode 110 should be transparent or substantiallytransparent to the emitted wavelengths. Commonly used transparent anodematerials include, but are not limited to, indium-tin oxide (ITO),indium-zinc oxide (IZO) tin oxide, aluminum- or indium-doped zinc oxide,magnesium-indium oxide, nickel-tungsten oxide, gallium nitride, zincselenide, zinc sulfide. When the EL emission occurs through the cathode170, the optical properties of the anode 110 are immaterial and anyconductive material, transparent, opaque or reflective can be used.Example conductors for this application include, but are not limited to,gold, iridium, molybdenum, palladium, and platinum.

The anode 110 can be deposited any suitable way such as evaporation,sputtering, chemical vapor deposition, or electrochemical processes.Anodes can be patterned using, e.g., conventional photolithographicprocesses.

The hole-injection material can serve to facilitate injection of holesinto the hole-transport layer 130. The hole-injection layer 120 can beformed of any hole-injection material including those that are commonlyused. Non-limiting examples of hole-injection materials areN,N′-diphenyl-N,N′-bis-[4-(phenyl-m-tolyl-amino)-phenyl]-biphenyl-4,4′-diamine(DNTPD), a phthalocyanine compound such as copper phthalocyanine,4,4′,4″-tris(3-methylphenylphenylamino)triphenylamine (m-MTDATA),N,N′-di(1-naphthyl-N,N′-diphenylbenzidine) (NPB),4,4′,4″-tris(N,N-diphenylamino)triphenylamine (TDATA),4,4′,4″-tris-(N-(naphthylen-2-yl)-N-phenylamino)triphenylamine(2-TNATA), polyaniline/dodecylbenzenesulfonic acid (Pani/DBSA),poly(3,4-ethylenedioxythiophene)/poly(4-styrenesulfonate) (PEDOT/PSS),polyaniline/camphor sulfonic acid (Pani/CSA),(polyaniline)/poly(4-styrenesulfonate) (PANI/PSS),tetracyanoquinonedimethane (TCNQ),2,3,5,6-tetrafluoro-tetracyano-1,4-benzoquinonedimethane (F4-TCNQ) andadditional hole-injection materials, such asdipyrazino[2,3-f:2′,3′-h]quinoxalinehexacarbonitrile (HATCN) aredescribed in U.S. Publication 2004/0113547 A1 and U.S. Pat. No.6,720,573.

The hole-injection material can be deposited using any suitableconventional method known in the art including, but not limited to,vacuum deposition, spin coating, printing, print screening, spraying,painting, doctor-blading, slot-die coating, and dip coating.

The hole-transport layer 130 can be formed of any hole-transportmaterial including those that are commonly used. Non-limiting examplesof suitable known hole-transport materials are carbazole derivatives,such as N-phenylcarbazole or polyvinylcarbazole,—N,N′-bis(3-methylphenyl-N,N′-diphenyl-[1,1-biphenyl]-4,4′-diamine(TPD), 4,4′,4″-tris(N-carbazolyl)triphenylamine (TCTA),(4,4′-(cyclohexane-1,1-diyl)bis(N,N-di-p-tolylaniline)) (TAPC), and—N,N′-di(1-naphthyl-N,N′-diphenylbenzidine) (NPB).

The hole-transport material can be deposited using any suitableconventional method known in the art including, but not limited to,vacuum deposition, spin coating, printing, print screening, spraying,painting, doctor-blading, slot-die coating, and dip coating.

The light-emitting layer 140 can comprise a substantially pure thin filmcomprising a compound of Formula 1 or a host matrix doped with acompound of Formula I. In instance in which the light-emitting layercomprises a host matrix, the host matrix can be any host matrix materialknown in the art. Non-limiting examples of host matrix materials includebis(4-(3,6-diphenyl-9H-carbazol-9-yl)phenyl)methanone,9-(4-(4,6-diphenylpyrimidin-2-yl)phenyl)-9H-carbazole,4-(4-diphenylaminophenyl)diphenylsulfone,9-(9-phenyl-9H-carbazol-3-yl)-9-p-tolyl-9H-fluorene-3-carbonitrile,3,5-di(9H-carbazol-9-yl)benzonitrile,2-(diphenylphosphinyl)-spiro[9H-fluorene-9,9′-quino[3,2,1-kl]phenoxazine],2,8-bis(diphenylphosphoryl)dibenzo[b,d]thiophene,4,4′-bis(carbazol-9-yl)biphenyl,4,4′,4″-tris(carbazol-9-yl)triphenylamine,2,6-bis(9,9-diphenylacridin-10(9H)-yl)pyrazine,1,3-bis(carbazol-9-yl)benzene,4,4′,4″-Tris(carbazol-9-yl)triphenylamine,4,4′-bis(carbazol-9-yl)biphenyl,9-(4-tert-butylphenyl)-3,6-bis(triphenylsilyl)-9H-carbazole,1,3,5-tri[(3-pyridyl)-phen-3-yl]benzene,2,8-bis(diphenylphosphoryl)dibenzo[b,d]thiophene,bis[2-(diphenylphosphino)phenyl]ether oxide,2,6-di(9H-carbazol-9-yl)pyridine,3′,5′-di(carbazol-9-yl)-[1,1′-biphenyl]-3,5-dicarbonitrile,4,4′-(9H,9′H-3,3′-bicarbazole-9,9′-diyl)bis(N,N-diphenylaniline),4′-(9H-carbazol-9-yl)biphenyl-3,5-dicarbonitrile,3′-(9H-carbazol-9-yl)biphenyl-3,5-dicarbonitrile,2,8-bis(diphenylphosphoryl)dibenzo[b,d]furan, and3,5-di(carbazol-9-yl)-1-phenylsulfonylbenzene. The compound of Formula 1can be present in the host material at a concentration of 1-20% w/w.

The light-emitting material can be deposited using any suitableconventional method known in the art including, but not limited to,vacuum deposition, spin coating, printing, print screening, spraying,painting, doctor-blading, slot-die coating, and dip coating.

Any suitable electron-transport material may be used to form theelectron-transport layer 150. As the electron-transport material, anyelectron-transporting material that can stably transport electronsinjected from an electron injecting electrode (cathode) may be used as amaterial for the electron-transport layer. Non-limiting examples ofuseful electron-transport materials may include quinoline derivativessuch as tris(8-quinolinorate)aluminum (Alq3),3-(biphenyl-4-yl)-4-phenyl-5-(4-t-butylphenyl)-1,2,4-triazole (TAZ),bis(2-methyl-8-quinolinato-N1,08)-(1,1′-biphenyl-4-olato)aluminum(BAlq), beryllium bis(benzoquinolin-10-olate) (Bebg2),9,10-di(naphthalene-2-yl)anthracene (ADN),1,3,5-Tris(3-pyridyl-3-phenyl)benzene (TmPyPB), and(3,3″,5,5″-tetra(pyridin-3-yl)-1,1′: 3′,1″-terphenyl (BmPyPhB).

The electron-transport material can be deposited using any suitableconventional method known in the art including, but not limited to,vacuum deposition, spin coating, printing, print screening, spraying,painting, doctor-blading, slot-die coating, and dip coating.

Any suitable electron-injection material may be used to form theelectron-injection layer 160. Non-limiting examples of electroninjecting materials useful for forming the electron-injection layer 160are LiF, NaCl, CsF, Li₂O, 8-hydroxyquinolinolato-lithium (Liq) and BaO.

The electron-injection material can be deposited using any suitableconventional method known in the art including, but not limited to,vacuum deposition, spin coating, printing, print screening, spraying,painting, doctor-blading, slot-die coating, and dip coating.

The cathode 170 can comprise any anodic material known to those of skillin the art. In certain embodiments, the anode comprises lithium,magnesium, calcium, aluminum, gold, indium, copper, silver, or acombination thereof. In certain embodiments, the anode comprisesaluminum.

The cathode 170 can be deposited using any suitable way such asevaporation, sputtering, chemical vapor deposition, or electrochemicalprocesses. Anodes can be patterned using, e.g., conventionalphotolithographic processes.

In certain embodiments, the OLED comprises thin layers ofITO/HATCN/TAPC/AIEgen 1/TmPyPB/LiF/Al, wherein HATCN and LiF serve asthe hole-injection and electron-injection layers, respectively; TAPC andTmPyPB serve as the hole-transport and electron-transport layers,respectively; AIEgen 1 serves as the light-emitting layer; and ITO andAl are used as the anode and electrode, respectively.

The luminescent devices described herein can be incorporated into a widevariety of consumer products, including flat panel displays, computermonitors, televisions, billboards, lights for interior or exteriorillumination and/or signaling, sensors, heads up displays, fullytransparent displays, flexible displays, cell phones, personal laptopcomputers, digital cameras, camcorders, viewfinders, micro-displays,vehicles, a large area wall, theater or stadium screen, or a sign.

The materials and structures described herein may have applications indevices other than OLEDs. For example, other optoelectronic devices suchas organic solar cells and organic photodetectors may employ thematerials and structures. More generally, organic devices, such asorganic transistors, may employ the materials and structures describedherein.

AIEgen 1 featuring a propeller shaped structure exhibits AIE properties(FIG. 5). When the sample of AIEgen 1 was dissolved in pure DMF solventat low concentration, the solution was completely non-emissive. However,with the addition of water, its emission increased with a dramatic˜27,000-fold enhancement when the water fraction reached 40%, while theluminescence intensity remained almost unchanged with further increaseof water fractions. The single crystal structure of AIEgen 1 bears avery twisted molecular conformation with the corresponding torsionangles of 31.23 (θ₁), 39.34 (θ₂), 39.32 (θ₃), 57.85 (θ₄), and 47.72(θ₅), respectively. Accordingly, the rotations of multiple flexible arylrotors are greatly restricted in different aggregate states, which isbelieved to block the radiationless consumption of the excitation energyand facilitates the radiative decay channel, and thus AIEgen 1 and thecompounds described herein can become highly emissive.

A large molecular dipole of D-A structures can yield intriguingphotoluminescence behavior depending on the solvent polarity due to theconversion between less polarized locally excited (LE) state andpolarized twisted intramolecular charge transfer (TICT) state. AIEgen 1demonstrated a strong solvatochromic effect. When the solvent polaritywas increased gradually from low-polarity hexane to high-polarityacetonitrile, the emission of its solution exhibited a dramaticbathochromic shift and the intensity gradually weakened due to thesusceptibility of the TICT state to various nonradiative quenchingprocesses. Meanwhile, its solution colors changed from bright blue innonpolar hexane over green, yellow and orange in lower polar solvents(such as ether, ethyl acetate, THF and DCM) and then to dark red in highpolar solvents (acetone, DMF and acetonitrile), thus covering the wholevisible region as shown in the CIE diagram obtained from the PL spectra(FIG. 6B), and allowing even a visual estimate of the solvent polarity.In sharp contrast, its absorption spectra displayed no obvious change asthe solvent polarity increased. Quantitatively, the relationship betweenthe Stokes shift (v_(a)−v_(f)) of the luminogen and solvent parameters,or the orientation polarizability f (ε, n) can be described by theLippert-Mataga equation:

${h{c\left( {v_{a} - v_{f}} \right)}} = {{h{c\left( {v_{a}^{0} - v_{f}^{0}} \right)}} + {\frac{2\left( {\mu_{e} - \mu_{g}} \right)^{2}}{a^{3}}{f\left( {ɛ,\ n} \right)}}}$

where h is Plank's constant, c is the velocity of light, f is theorientational polarizability of the solvent, v_(a) ⁰−v_(f) ⁰ correspondsto the Stokes shifts when f is zero, μ_(e) is the excited-state dipolemoment, μ_(g) is the ground-state dipole moment, a is the solventOnsager cavity radius, and ε and n are the solvent dielectric and thesolvent refractive index, respectively (Table 2, FIG. 18). As shown inFIG. 6B, the experimental data of AIEgen 1 obeys a good linearrelationship expected by Lippert-Mataga equation in the whole range ofsolvent polarity, further confirming its typical TICT character.Additionally, obvious charge separation in its natural transitionorbitals (NTO) of the first singlet excited state also verified thelarge molecular dipole of AIEgen 1 further reflecting its ICT character(FIG. 7). The aforesaid solvatochromic PL behavior is essentially avisualization for marked solvent polarity changes which takes place on amolecular-microscopic level. It is more appealing that the compoundsdescribed herein could also achieve the visualization of subtle polaritychanges, details see below.

In general, the luminescence of organic compounds in solution state isquenched with the increase of temperature. However, it is intriguingthat the compounds described herein can achieve a continuously enhancedemission by increasing temperature. From another perspective, thistemperature effect is also powerful evidence to reinforce that the TICTprocess is really involved. Typically, in THF solvent with a moderatepolarity, two discernable bands centered at 556 and 596 nm related tothe LE state and the TICT state, respectively, could be observed. Asdemonstrated in FIG. 9, increasing the temperature from 29° C. to 47° C.led to a change of their relative intensities. Additionally, there is anexcellent linearity between their intensity ratio (λ₅₅₆/λ₅₉₆) and thetemperature in the range from 29° C. to 47° C., including a vitalphysiological temperature range, suggesting that the present ratiometricsystem may be useful for the quantitative determination of temperature.More interestingly, a noticeable luminescence color transition from darkorange to bright yellow was accompanied with the above temperatureelevation process. Therefore, the compounds described herein can realizecolorimetric and ratiometric temperature detection. It has beenrecognized that solvent polarity is heavily temperature-dependent. Inweakly polar toluene, similar intensity-intensified and blue-shiftedtendency could be observed with the increase of temperature, while thesevariations were comparatively more conspicuous and were accompanied bystriking color changes in relatively higher polarized solvents, i.e.dichloroethane and o-dichlorobenzene, as shown in FIG. 10.

Herein, it is noteworthy to mention that polarity is an importantparameter in chemistry, nanotechnology, and even life science. Inbiological systems, especially at the cellular level, polaritydetermines the interaction activity of large numbers of proteins andenzymes or reflects the permeability of membrane compartments.Furthermore, abnormal changes in polarity are closely linked withdisorders and diseases (e.g., diabetes, liver cirrhosis). However, theenvironmental polarity change in many cases is relatively subtle,especially for the above biological systems and the aforementionedtemperature-dependent systems, thus it is very difficult to realize itsaccurate measurement in a straightforward manner, let alone itsmacroscopic visualization. Therefore, the compounds described herein,involving simple ratiometric measurement of fluorescence signals,readily realized a dramatic amplification of the subtle polarity changeas a function of temperature. Additionally, this microcosmic change hasbeen well presented by macroscopic color changes of the system.Therefore, the present signal amplification and visualization methodprovides a valuable tool for the measurement of subtle polarity change.In another aspect, thermochromic solutions of the compounds describedherein, such as AIEgen 1, also allow a simple quantitative determinationof the temperature dependence, thus possessing great potential to beused as luminescent thermometer. In order to test its response range andfacilitate its application, we have selected tetraethylene glycoldimethyl ether (TRIEDM) with a very high boiling point of 275° C. andideal stability as the solvent. As shown in FIG. 11, the emission bandof AIEgen 1 gradually blue shifted and the corresponding intensity wascontinuously enhanced with the increase of temperature. Advantageously,the luminescence color also exhibited obvious conversion from orange tobright yellow-green. It is reasonable to predict that the above changetendency would be continuous if temperature condition permits and itssolution colors likely cover the whole visible region as shown in theCIE diagram in FIG. 11C. Moreover, there is also a good linearrelationship between the intensity ratio (λ₅₃₅/λ₆₀₀) and the temperaturein a wide range of 25 to 175° C. It should be mentioned that the abovetemperature-dependent emission evolution and color conversion arecompletely reversible. Such intriguing properties inspired us tofabricate a simple liquid thermometer by utilizing the above TRIEDMsolution system. As illustrated in FIG. 11D, when we heated the abovesolution from the top and synchronously cooled it from the bottom,apparent color changed pattern, corresponding to specific temperaturegradient, could be directly observed with our naked eyes. This is only avery simple trial but it is reasonable to anticipate that the abovecolor switching should be much more prominent if higher temperature canbe achieved. In light of the excellent properties, our system should bea promising candidate for high performance thermometers with a widedetection range and high upper limit.

Thus, provided herein is a method for measuring the temperature, themethod comprising measuring the fluorescence emission of a samplecomprising a compound described herein; and determining the temperaturebased on the measured fluorescence emission. The step of determining thetemperature based on the measured fluorescence can comprise comparingthe measured fluorescence to fluorescence of a standardized curve orcomparing to the measured fluorescence to a color chart. The measuredtemperature can be any temperature. In certain embodiments, the measuredtemperature is in the range of −100 to 350° C. In certain embodiments,the measured temperature in the range of −50 to 300° C., 0 to 300° C., 0to 250° C., 0 to 200° C., 10 to 200° C., 20 to 200° C., 20 to 180° C.,25 to 175° C. or higher.

Also provided is a device for measuring the temperature comprising thecompound described herein and a solvent. In certain embodiments, thesolvent is an organic solvent. The selection of the organic solvent andits respective boiling point can be selected based on the desiredtemperature monitoring range. In certain embodiments, the boiling pointof the solvent is 50 to 500° C., 100 to 400° C., 100 to 300° C., 100 to300° C., 150 to 300° C., or 200 to 300° C. In certain embodiments, thesolvent is TRIEDM.

The underlying mechanism of the thermochromic PL of the compoundsdescribed herein was then investigated, with the goal of providing aninitial guideline for the design of new thermochromic materials. Takingall the experimental data together, we proposed that raising temperaturewill lead to the increase of solvent hydrophobicity, thus benefiting theLE state prone to planar geometry and resulting in intensified emissionintensities and blue-shifted luminescence. Given that temperatureswitching is considered to induce dynamic changes in molecularstructures. Considering there are multiple flexible aryl rotors in thecompounds described herein, various conformations of the excited stateS1 were attempted. Ultimately, it was observed that the central planeformed by atoms C16, N2 and C25 is the pivot to determine the flexibleconformation, and is also the critical position linking the chargeseparated donor and acceptor units. Upon excitation to S1, the moleculerotates around the N2-C25 bond, and the associated C16-N2-C25-C30dihedral angle varies from ˜30° to ˜90°, thus possessing a more twistedconformation as demonstrated in FIG. 12A. Combined with the mostpopulated transitions of molecular orbitals, the twisting degree ofmolecular conformations could be well elucidated by the variation ofcentral dihedral angle C16-N2-C25-C30. In order to clarify its influenceon the photoluminescence, the PL spectra of eight differentconformations was calculated by scanning different twisting angles ofC16-N2-C25-C30. As shown in FIG. 12C, a gradual red shift andattenuation of photoluminescence could be observed with the dihedralangle varying from 0° to 90°. These results revealed that more planarconformation should greatly facilitate the fluorescence emission. Thepotential energies of these eight conformations in the excited stateswas calculated. The potential energy of the planar conformation with 0°is about 14 kcal/mol higher than that of the twisted conformation with90°, thereby further indicating much higher stability of the latter. Thetheoretical calculations together with the evidences from thethermochromic study reinforced our previous envision that thetemperature strongly influenced the dynamic equilibrium between the LEand TICT excited states and higher temperature is suggested tofacilitate the stability of planar geometry with LE character, furtherresulting in blue-shifted and enhanced photoluminescence.

Excitingly, this compound is very sensitive to the external shear forcestimulus and exhibits attractive tribochromic PL behavior (FIG. 13). Wefound that the solid showed red-shifted and remarkably enhanced emissionwhen the powder was ground under shearing force. Upon grinding, itsemission color changed from blue to yellow-green with the maximalfluorescent peak shifted from 480 nm to 509 nm, and the correspondingquantum yield also dramatically increased up to 86% from the original52% (FIGS. 13A and 13C). Surprisingly, the color transition aftergrinding could be directly observed with naked eyes in daylight (FIG.14). When the ground powder was exposed to dichloromethane (DCM) vapor,the original blue state could be restored completely as the PL spectraverified, indicative of a reversible tribo-responsive process. Given itsexcellent triochromic PL behavior, the practical application inrewritable paper was explored. By immersing the filter paper into theDCM solution of AIEgen 1 and then drying by blower, a blue emissiverewritable paper was prepared, on which legible yellow-green letterssuch as “AIE” with a sharp rod could be inscribed. When exposing thefilter paper in DCM atmosphere for a few minutes, the written letterscan be easily erased. And the above writing-erasing process could berepeated many times. Accordingly, the compounds described herein couldpotentially be applicable for security inks and papers. Thus, providedherein is rewritable paper system comprising paper and a compounddescribed herein. Also provided in a security ink comprising a compounddescribed herein.

Powder X-ray diffraction (pXRD) measurement was performed on an AIEgen 1sample in different states to examine the tribochromic PL mechanism. Asdemonstrated in FIG. 13B, the pristine state of AIEgen 1 exhibits sharpand intense diffraction peaks, suggesting a well-defined crystallinestate; while relatively weak reflections could be observed aftergrinding, indicative of significant destruction of crystalline state bymechanical forces. In this state, the amorphous species should bepredominantly produced. Upon fuming in the DCM atmosphere, the originalsharp signals could be restored, which reveals the recovery of thecrystalline state. Therefore, the observed tribochromic PL behavior ofAIEgen 1 is explicitly involved in a reversible morphologicaltransformation between the blue crystalline state and the amorphousyellow-green state.

Given that the compounds described herein can respond to anisotropicshearing force, the compound's responsive behavior to isotropichydrostatic pressure was examined. As shown in FIG. 15, AIEgen 1suffered remarkable and continuous color variation over three stagesfrom blue to yellow and then to orange with increasing in situ pressure.Concomitantly, the fluorescence spectra exhibited a gradual red shiftfrom 481 nm to 588 nm (FIG. 15B), but its intensity decreasedcontinuously, which is noticeably different from that of its groundstate. However, once the pressure was released, it gradually revertedback to the initial state (FIG. 15C and FIG. 16). To probe thestructural change during the above piezochromic PL process, an in situhigh-pressure Raman experiment was performed on AIEgen 1. Asdemonstrated in FIG. 15D and FIG. 17, all the Raman peaks displayedblue-shift with elevated external pressure, which is presumablyattributed to the simultaneously shortened bond lengths and decreasedintermolecular distances.

Combined with the DFT calculation results (Table 3, FIG. 21), the peaksat 709, 723, and 740 cm⁻¹ are attributed to the C—H bond off-planewagging vibrations, and their respective intensities gradually decreasedwith the increase of pressure; while the peaks ascribed to breathingvibrations of benzene ring at 997 cm⁻¹ (P1, P2 and P4) and 1002 cm⁻¹ (P3and P5) gradually blue shifted and fused into one single peak with theincrease of high pressure. Accordingly, it's reasonable to think thatthe intermolecular interactions would be enhanced under increasinghydrostatic pressure and this isotropic force mainly influences theintermolecular interactions, where all the molecules are squeezed into aquite uncomfortable condition during the compression process. Once thepressure was released, it can return to the initial state.

The above observations raise a question: why the mechanical grinding andhydrostatic pressure trigger distinct luminescence alterations? Theanalyses of crystal structure were expected to provide some clues toaddress this issue. As shown in FIGS. 17 and 18, multiple weakintermolecular C—H . . . π interactions (distances ranging from 3.06 to3.43 Å) between the adjacent molecules could be observed, which play avital role in fixing the orientation of the diamine donor and thetriarylboron acceptor (FIG. 17A). Additionally, it was noted that theintermolecular amine donor and the boron acceptor units get very closeto each other (FIG. 17B), which is enough to cause intermolecular chargetransfer processes. In the molecular packing, the molecules form orderedbut very loose arrangements (FIG. 17C). Accordingly, regarding themechanism of tribochromic PL behavior, it was presumed that these weakintermolecular interactions and the intermolecular charge transferprocesses should be perturbed by the anisotropic stimulus of mechanicalgrinding, which is also accompanied by the intramolecular conformationalplanarization, and both factors synergistically result in a red-shiftedand remarkably enhanced emission. While the situation is presumablydifferent for the piezochromic PL process. The isotropic high pressureis strong enough to squeeze the adjacent molecules close enough thatinevitably generates intermolecular π-π interactions and can facilitateintermolecular charge transfer processes, thus jointly leading to thered-shifted and annihilated emission.

The electrochemical behavior of AIEgen 1 was investigated by cyclicvoltammetry and square-wave voltammetry in deaerated CH₂Cl₂ containing10⁻¹ mol/L n-Bu₄NPF₆ as the supporting electrolyte (FIG. 22). AIEgen 1exhibited two well-defined reversible oxidation peaks at 0.81 and 1.10 V(vs. Ag/Ag⁺), respectively, and one quasi-reversible reduction peak at−2.00 V (vs. Ag/Ag⁺). The oxidation peaks are ascribed to stepwiseoxidation of the diamine donors and the reduction process is attributedto reduction of the diarylboron acceptor. In addition, the HOMO and LUMOenergy levels of AIEgen 1 were determined to be −5.18 and −2.34 eV,respectively, and the HOMO-LUMO band gap was 2.84 eV (Table 4, FIG. 24).

Interestingly, AIEgen 1 can also respond to the external electricstimulus and exhibited remarkable change in its electronic spectra inthe near-infrared (NIR) region and different colors associated with itsdifferent oxidation states during the in situ spectroelectrochemicalmeasurements (FIG. 23). As demonstrated in FIG. 23, the completelyreversible conversion among three different colors could be readilyachieved by modulating the redox potentials of AIEgen 1, i.e. lightyellow, vivid green, and dark green, corresponding to neutral,monocationic, and dicationic states, respectively, which could bedirectly observed with naked eyes. Therefore, the above distinctproperties of AIEgen 1 indicate that this compound has great potentialto be used as an electroswitchable electrochromic material. Regardingits emission spectra, it can also realize a transformation from turn-onstate to turn-off state upon slow oxidation to the mono-cationic statewith its orange luminescence gradually weakened (FIG. 23C), alsopointing to its potential application in information recording andstorage devices.

In light of its excellent luminescent behavior of AIEgen 1 in the solidstate, its potential application as solid-state emitter was evaluated.Thermogravimetric analysis (TGA) was also performed to analyze thethermal properties of AIEgen 1 under nitrogen atmosphere, as shown inFIG. 25 and Table 4 (FIG. 24). The pertinent data indicated that AIEgen1 exhibits desirable thermal stability with a decomposition temperatureup to 376° C., thus demonstrating that this compound is stable enoughfor thermal evaporation. Its film was prepared by vacuum evaporation. Asshown in FIG. 26, its film exhibited a very bright yellow-greenfluorescence (τ=6.9 ns) with a maximal peak at 501 nm and a very highquantum yield of 84%, thus indicating very similar properties to itsground amorphous state we discussed above. Accordingly, we furtherfabricated non-doped OLED with the device configuration of indium tinoxide ITO/HATCN (5 nm)/TAPC (25 nm)/AIEgen 1 (35 nm)/TmPyPB (55 nm)/LiF(1 nm)/Al (120 nm), wherein HATCN and LiF serve as the hole-injectionand electron-injection layers, respectively; TAPC and TmPyPB serve asthe hole-transport and electron-transport layers, respectively; AIEgen 1serves as the light-emitting layer; and ITO (indium tin oxide) and Alare used as the anode and electrode, respectively. The schematic energylevel diagrams of the devices, EQE (external quantum efficiency) versusluminance curves, the electroluminescence (EL) spectra, the currentdensity-voltage-luminance (J-V-L) characteristics, voltage-dependent ELspectra, the current efficiency and power versus luminance curves of thenon-doped OLEDs are presented in FIG. 27. The key device performancesare summarized in Table 5 (FIG. 28). The EL spectra of AIEgen 1 is closeto that of the nondoped PL spectrum (vacuum-deposited) and very stableat various driving voltages, indicating that the emissive excitons werewell confined in the emitting layer. The EL shows a bright greenemission peak of 516 nm and CIE coordinate of (0.289, 0.551). Themaximum luminance (L_(max)), current efficiency (η_(c)), powerefficiency (η_(p)), and EQE values are as high as 4622 cd m⁻², 16.23 cdA⁻¹, 11.69 lm W⁻¹, and 5.22%, respectively. Impressively, the EQE value(5.22%) is practically reaching the theoretical limit value oftraditional organic emitters, which makes the compounds describedherein, and parituclarly AIEgen 1, a promising candidate for OLEDapplication.

EXAMPLES

The following examples are illustrative of the presently describedsubject matter and are not intended to be limitations thereon.

Preparation of AIEgen 1

The general synthetic route to AIEgen 1 is outlined above. Allmanipulations were carried out under a dry argon atmosphere usingstandard Schlenk techniques, unless stated otherwise. Solvents werepre-dried and distilled under argon prior to use, except those useddirectly for spectroscopic measurements, which were of spectroscopicgrade. The precursor 1 was prepared according to procedure described inthe literature (J. Phys. Chem. A, 2015,119, 1933-1942.). Other reagentswere purchased and used as received.

Synthesis of AIEgen 1:N¹-(4-bromophenyl)-N,N⁴,N⁴-triphenylbenzene-1,4-diamine (Precursor 1)(490 mg, 1.00 mmol) was dissolved in anhydrous THF (30 mL) undernitrogen, and the resulting mixture was cooled to −78° C. To thissolution, n-BuLi (0.5 mL, 2.5 M in hexane) was added slowly and theresulting solution was stirred for 1 h at −78° C. Dimesitylboronfluoride (402 mg, 1.5 mmol) was dissolved in THF (10 mL) and then slowlyadded to the reaction solution at −78° C. The mixture was allowed towarm to room temperature with stirring overnight. The solvent was thenremoved in vacuo, and the residue was purified by chromatography onsilica gel (petroleum ether/dichloromethane 8:1, v/v). The product wasprecipitated from a solution in CH₂Cl₂ by adding MeOH to give 547 mg(79%) of AIEgen 1 as a yellow-green powder. ¹H NMR (CDC₃, 400 MHz, ppm):δ 7.35 (d, J=8 Hz, 2H), 7.18-7.31 (m, 8H), 6.98-7.10 (m, 11H), 6.90 (d,J=8 Hz, 2H), 6.79 (s, 4H), 2.28 (s, 6H), 2.06 (s, 12H); ¹³C NMR (CDC₃,100 MHz, ppm): 151.4, 147.7, 146.6, 144.2, 141.9, 141.2, 140.7, 138.7,137.9, 129.4, 129.2, 129.1, 128.0, 127.1, 125.6, 124.9, 124.1, 124.0,122.7, 118.9 (Ar); HRMS (MALDI-TOF): m/z: [M]+ calcd for C₄₈H₄₅BN₂ ⁺:660.3676; found: 660.3665.

What is claimed is:
 1. A compound having the Formula 1:

wherein each of Ar¹, Ar², Ar³, Ar⁴, Ar⁵, Ar, and Ar⁷ is independentlyselected from the group consisting of aryl and heteroaryl.
 2. Thecompound of claim 1, wherein the compound is represented by the Formula2:

wherein each of m and n is independently 1, 2, 3, or 4; R¹ and R² foreach instance is independently selected from the group consisting ofhydrogen, halide, nitrile, nitro, —OR, —SR, —NR₂, —(C═O)R, —(C═O)OR,—(C═O)NR₂, —N(R)(C═O)R, —O(C═O)R, —N(R)(C═O)OR, —O(C═O)NR₂, —SO₂R,—SO₂NR₂, alkyl, cycloalkyl, alkenyl, alkynyl, aryl, heterocycloalkyl,and heteroaryl; or two instance of R¹ taken together form a 5-6 memberedcycloalkyl, heterocycloalkyl, aryl, or heteroaryl; or two instance of R²taken together form a 5-6 membered cycloalkyl, heterocycloalkyl, aryl,or heteroaryl; or one instance of R¹ and one instance of R² takentogether form a covalent bond; and R for each instance is independentlyselected from the group consisting of hydrogen, alkyl, cycloalkyl,alkenyl, alkynyl, aryl, heterocycloalkyl, and heteroaryl; or twoinstances of R taken together form a 3-6 membered heterocycloalkyl. 3.The compound of claim 1, wherein the compound has the Formula 3:

wherein each of m and n is independently 1, 2, 3, or 4; each of o, p, q,t, and u is independently 1, 2, 3, 4, or 5; R¹ and R² for each instanceis independently selected from the group consisting of hydrogen, halide,nitrile, nitro, —OR, —SR, —NR₂, —(C═O)R, —(C═O)OR, —(C═O)NR₂,—N(R)(C═O)R, —O(C═O)R, —N(R)(C═O)OR, —O(C═O)NR₂, —SO₂R, —SO₂NR₂, alkyl,cycloalkyl, alkenyl, alkynyl, aryl, heterocycloalkyl, and heteroaryl; ortwo instance of R¹ taken together form a 5-6 membered cycloalkyl,heterocycloalkyl, aryl, or heteroaryl; or two instance of R² takentogether form a 5-6 membered cycloalkyl, heterocycloalkyl, aryl, orheteroaryl; or one instance of R¹ and one instance of R² taken togetherform a covalent bond; R³, R⁴, R⁵, R⁶, and R⁷ for each instance isindependently selected from the group consisting of hydrogen, halide,nitrile, nitro, —OR, —SR, —NR₂, —(C═O)R, —(C═O)OR, —(C═O)NR₂,—N(R)(C═O)R, —O(C═O)R, —N(R)(C═O)OR, —O(C═O)NR₂, —SO₂R, —SO₂NR₂, alkyl,cycloalkyl, alkenyl, alkynyl, aryl, heterocycloalkyl, and heteroaryl; orone instance of R⁴ and on instance of R⁵ form a covalent bond; or oneinstance of R³ and one instance of R¹ taken together form a covalentbond; or one instance of R³ and one instance of R⁴ taken together form acovalent bond; or one instance of R¹ and one instance of R⁵ takentogether form a covalent bond; or one instance of R² and one instance ofR⁵ taken together form a covalent bond; or one instance of R² and oneinstance of R⁷ taken together form a covalent bond; or one instance ofR⁶ and one instance of R⁷ taken together form a covalent bond; and R foreach instance is independently selected from the group consisting ofhydrogen, alkyl, cycloalkyl, alkenyl, alkynyl, aryl, heterocycloalkyl,and heteroaryl; or two instances of R taken together form a 3-6 memberedheterocycloalkyl.
 4. The compound of claim 3, wherein each of m and n isindependently 1 or 2; each of o, p, q, t, and u is independently 1, 2,or 3; R¹ and R² for each instance is independently selected from thegroup consisting of hydrogen, halide, nitrile, nitro, —OR, —NR₂, alkyl,cycloalkyl, alkenyl, alkynyl, aryl, heterocycloalkyl, and heteroaryl;R³, R⁴, R⁵, R⁶, and R⁷ for each instance is independently selected fromthe group consisting of hydrogen, halide, nitrile, nitro, —OR, —NR₂,alkyl, cycloalkyl, alkenyl, alkynyl, aryl, heterocycloalkyl, andheteroaryl; and R for each instance is independently selected from thegroup consisting of hydrogen, alkyl, aryl, and heteroaryl.
 5. Thecompound of claim 1, wherein the compound has the Formula 4:

each of R³, R⁴, R⁵, R⁶, and R⁷ is independently selected from the groupconsisting of hydrogen, halide, nitrile, nitro, —OR, —NR₂, alkyl,cycloalkyl, alkenyl, alkynyl, aryl, heterocycloalkyl, and heteroaryl,wherein R is alkyl, aryl, or heteroaryl.
 6. The compound of claim 1,wherein the compound has the Formula 5:

wherein each of m and n is independently 1 or 2; each of R¹ and R² foreach instance is independently selected from the group consisting ofhydrogen, halide, nitrile, nitro, —OR, —NR₂, —(C═O)R, —(C═O)OR,—(C═O)NR₂, —N(R)(C═O)R, —O(C═O)R, —N(R)(C═O)OR, —O(C═O)NR₂, alkyl,cycloalkyl, alkenyl, alkynyl, aryl, heterocycloalkyl, and heteroaryl;R³, R⁴, R⁵, R⁶, and R⁷ for each instance is independently selected fromthe group consisting of hydrogen, halide, nitrile, nitro, —OR, —NR₂,—(C═O)R, —(C═O)OR, —(C═O)NR₂, —N(R)(C═O)R, —O(C═O)R, —N(R)(C═O)OR,—O(C═O)NR₂, alkyl, cycloalkyl, alkenyl, alkynyl, aryl, heterocycloalkyl,and heteroaryl; and R for each instance is independently selected fromthe group consisting of hydrogen, alkyl, cycloalkyl, alkenyl, alkynyl,aryl, heterocycloalkyl, and heteroaryl; or two instances of R takentogether form a 3-6 membered heterocycloalkyl.
 7. The compound of claim6, wherein each of R⁶ and R⁷ for each instance is independently selectedfrom the group consisting of hydrogen, halide, —OR, alkyl, cycloalkyl,alkenyl, alkynyl, aryl, heterocycloalkyl, and heteroaryl.
 8. Thecompound of claim 7, wherein each of R³, R⁴, and R⁵ are independentlyselected from hydrogen, —OR, —NR₂, alkyl, alkynyl, aryl, and heteroaryl;and R for each instance is independently aryl or heteroaryl.
 9. Thecompound of claim 1, wherein the compound has the Formula 6:

wherein each of m and n is independently 1 or 2; each of t and u isindependently 1, 2, or 3; R¹ and R² for each instance is independentlyselected from the group consisting of hydrogen, halide, nitrile, nitro,—OR, —SR, —NR₂, —(C═O)R, —(C═O)OR, —(C═O)NR₂, —N(R)(C═O)R, —O(C═O)R,—N(R)(C═O)OR, —O(C═O)NR₂, —SO₂R, —SO₂NR₂, alkyl, cycloalkyl, alkenyl,alkynyl, aryl, heterocycloalkyl, and heteroaryl; or two instance of R¹taken together form a 5-6 membered cycloalkyl, heterocycloalkyl, aryl,or heteroaryl; or two instance of R² taken together form a 5-6 memberedcycloalkyl, heterocycloalkyl, aryl, or heteroaryl; or one instance of R¹and one instance of R² taken together form a covalent bond; or oneinstance of R² and one instance of R⁶ taken together form a covalentbond; R⁶ and R⁷ for each instance is independently selected from thegroup consisting of hydrogen, halide, nitrile, nitro, —OR, —SR, —NR₂,—(C═O)R, —(C═O)OR, —(C═O)NR₂, —N(R)(C═O)R, —O(C═O)R, —N(R)(C═O)OR,—O(C═O)NR₂, —SO₂R, —SO₂NR₂, alkyl, cycloalkyl, alkenyl, alkynyl, aryl,heterocycloalkyl, and heteroaryl; or one instance of R⁴ and on instanceof R⁵ form a covalent bond; or one instance of R³ and one instance of R¹taken together form a covalent bond; or one instance of R³ and oneinstance of R⁴ taken together form a covalent bond; or one instance ofR¹ and one instance of R⁵ taken together form a covalent bond; or oneinstance of R² and one instance of R⁵ taken together form a covalentbond; or one instance of R² and one instance of R⁷ taken together form acovalent bond; or one instance of R⁶ and one instance of R⁷ takentogether form a covalent bond; and R for each instance is independentlyselected from the group consisting of hydrogen, alkyl, cycloalkyl,alkenyl, alkynyl, aryl, heterocycloalkyl, and heteroaryl; or twoinstances of R taken together form a 3-6 membered heterocycloalkyl. 10.The compound of claim 9, wherein each of R¹ and R² for each instance isindependently selected from the group consisting of hydrogen, halide,nitrile, nitro, —OR, —NR₂, alkyl, cycloalkyl, alkenyl, alkynyl, aryl,heterocycloalkyl, and heteroaryl; each of R⁶ and R⁷ for each instance isindependently selected from the group consisting of hydrogen, halide,nitrile, nitro, —OR, —SR, —NR₂, alkyl, cycloalkyl, alkenyl, alkynyl,aryl, heterocycloalkyl, and heteroaryl; and R for each instance isindependently selected from the group consisting of hydrogen, alkyl,cycloalkyl, alkenyl, alkynyl, aryl, heterocycloalkyl, and heteroaryl; ortwo instances of R taken together form a 3-6 membered heterocycloalkyl.11. The compound of claim 9, wherein the compound has Formula 7:

wherein each of R⁶ and R⁷ for each instance is independently selectedfrom the group consisting of hydrogen, halide, —OR, alkyl, cycloalkyl,alkenyl, alkynyl, aryl, heterocycloalkyl, and heteroaryl.
 12. Thecompound of claim 1, wherein the compound has the Formula 8:

wherein each of R⁶ and R⁷ is independently selected from hydrogen andalkyl.
 13. The compound of claim 12, wherein each of R⁶ and R⁷ ismethyl.
 14. A method of preparing the compound of claim 1, the methodcomprising: contacting a compound of Formula 1a:

wherein each of Ar¹, Ar², Ar³, Ar⁴, and Ar⁵ is independently selectedfrom the group consisting of aryl and heteroaryl; and M is lithium,sodium, MgBr, or a Zn species; with a compound of Formula 1b:

wherein each of Ar⁶, and Ar⁷ is independently selected from the groupconsisting of aryl and heteroaryl; and X is a halide; thereby formingthe compound of claim
 1. 15. The method of claim 14, wherein thecompound of Formula 1a is:

and the compound of Formula 1b is:


16. A method for detecting a change in a physical-chemical parameter ina test sample comprising the compound of claim 1, the method comprising:providing the test sample; measuring the fluorescence emission of thetest sample; comparing the measured fluorescence emission of the testsample with the fluorescence emission of a control sample comprising thecompound of claim 1 in a ground state; and based on the difference influorescence emission between the test sample and the control sampledetermine whether there is a change in the physical-chemical parameter,wherein the ground state is the fluorescence emission of the compound ofclaim 1 in the absence of the physical-chemical parameter.
 17. Themethod of claim 16, wherein the physical-chemical parameter is at leastone parameter selected from the group consisting of the temperature ofthe test sample, the sheer force exerted on the test sample, theoxidation state of the test sample, the solvent in the test sample; andthe isotropic hydrostatic pressure of the test sample.
 18. The methodclaim 16, wherein the compound has the formula:


19. An organic light emitting diode (OLED) comprising the compound ofclaim
 1. 20. The OLED of claim 19, wherein the compound has the formula: